>
I can't see Xi stepping into Ukraine. >

what would happen if Xi goes to Kyiv to show his public support for Zelensky? >

That would be counter to what he has been doing: increasing support for Russia.  source >

then what would be the appropriate way for Xi to respond to Zelensky's invitation? >

Nothing. China is in that weird spot no matter what action they choose, it will do poorly.
1) If China support Russia--well, possible sanctions, possible nothing. West opinion of China will not improve.
2) If China support Ukraine-- No additional benefits, hostile Russia on their northern border, western opinion will not improve--and certainly wouldn't help get Taiwan back. if Russia collapses/fall into a western controlled puppet (Yeltsin II), it wouldn't help China either. 
So basically geopolitics dictate China to sit on the fence. No matter who wins in this war, it is unlikely they can cut China out from the future. 
So the answer is to do nothing. >

China also undermines their own geopolitical position if they support Russia too strongly. It tarnishes their legitimacy if they don't support territorial integrity and opens the door for more nations to support Taiwanese independence. >

Taiwan is always considered part of China from China point of view. In their eyes, you can support other countries territorial integrity and demand eventual reunification of Taiwan. 
But lets face it, it is not like China (and everybody else) took on Americans when they stormed Iraq or when Russians charged Georgia. Talk is cheap. 
Most of Taiwan's western allies will not change their mind of China-Taiwan issue, nor will China. Whatever happen in Ukraine is irrevlant. >

Yes that’s the point. 
Supporting Russia is saying territorial integrity is not important because they have invaded and annexed parts of a neighbor multiple times. China’s justification for its Taiwan policy is territorial integrity. 
You’re right that it won’t make a difference though. No one in East Asia really trusts China anyway aside from maybe Singapore, so no one expects them to have consistency in their policies. >

Singapore does not trust China. Singapore’s foreign policy is to trust no one. >

Ukraine about to join the Belt and Road Initiative >

They were already part of it, but the war derailed the ongoing investment project.
As a side note, it's very likely Ukraine will take advantage of Chinese help for reconstruction. They don't have to be tied solely to the West for what's going to be a long, costly rebuild of their country. >

Don’t forget that technology transfers from Ukraine — not Russia — formed the basis of many Chinese military equipment. >

Yes. The most striking example is probably the Liaoning, the first Chinese aircraft carrier that is in fact the rebuilt Ukrainian/ex-Soviet Varyag kutnezsov-class carrier (though bought under cover as a floating casino). >

Y'all gonna have an aneurysm when you find out Ukraine and China have good relations. >

Welcome to the black and white world of the Reddit hive mind. >

Who are you declaring yourself superior to in this comment? >

clearly the implication is the average redditor >

Vague response from Xinnie the Pooh about how much China cares about 'world peace' but respectfully declines to help facilitate it actively, incoming in 3,2,1... >

We are just now hearing that China is currently Bing Chilling on the situation. >

Good move.  Make him a global focal point. >

It’s probably just a posture. Putin is pretending he hope for peace, all while making demands that are unreasonable and blame it on Ukraine for not accepting it. To counter it, call them out and make their own counter-posture, like "You hope for peace, you say? We’re the one actually trying to get a just peace here," is a pretty book move. >

Lots of outright no chance responses, and frankly I expect it to go that way. A few counterpoint, though none I expect would be enough to sway him; that said I'm not intimately knowledgeable on the overall dynamics, and dumb enough to know my gut could be wrong.
A few things that may be relevant (and most assume a Ukraine win, though the unfortunate possibility that it could be years and it is not assured what will happen with Russian "claimed" territories, though I think and hope they will stay with Ukraine where they belong, but I don't think it's necessarily a major factor here):
-ukraine will need to rebuild, China is heavily reliant on exports that will be needed, from appliances to cement to solar panels to vehicles to steel. Cement alone is interesting as China has significant excess capacity.
-russia is on the decline, Ukraine has already won the respect of the West. There will be money for rebuilding, which China will gladly take of Ukraine will spend it with them. China also wants money from the west and this could be an opportunity to curb the West's shying away (both accepting the talk and future help on the rebuild). Russian decline, likely financial issues, diminished workforces, and limited allies with significant producing capacitors in a variety of goods means that China will need to make up for less trade in some areas and Russian limited options mean a disgruntled Putin or other won't have much for alternatives. 
-if/when Russia loses, and/or Putin is replaced there will be repercussions. The blame will go to Putin and those who chose a war that "shouldn't have been started" so in hindsight the visit would not be viewed as badly as it appears now. Arguably there is evidence of such feelings already. Also, while China may not want Russia to lose there are still benefits to China (More powerful in the eastern sphere). And, while a long shot, if Putin is recognizing winning is unlikely or too costly (monetarily, politically, etc), China accepting could be good for him (an excuse to use, additional info/intelligence even if Putin hasn't seen the light). If China accepts it doesn't mean they will do anything to help, so this alone could be a path to the meet helping.
-xi has no skin in the game. He will do what is best for him and China. It makes sense to at least see what Ukraine thinks they have to offer.
Just to reiterate I expect the answer will be no. But that doesn't mean I have a clue, or that a no today couldn't turn into a yes later or at least help backchannel correspondence (including with Russia, which may inform xi of things that play a role in his decision; so even a no could benefit Ukraine by stirring up other things for Russia to focus on or dissenters to speculate about). That's my 2¢, which frankly may be worth less than rubles. >

China will come only if it involves rebuilding infrastructure. They love building things and linking trade routes. Mostly for their own benefits ofc >

Just like everyone else my guy. >

Suddenly they'll be a local incident that will require his undivided attention at home.. >

Watch the meeting between xi and Putin in Uzbekistan on sept 15 2022. 
It was Xi’s first overseas visit in over 1000 days. 
He was supposed to go to saudi to get them to make payments in yuan instead of dollars but he went to visit Putin instead. 
3 things stand out 
Notice the fanfare when xi shows up (30 piece band, dancing girls, the big motorcade) and compare it to when Putin shows up.   He is met by one CCP official.  
Then notice the fact that despite his paranoia of being poisoned and of Covid, Putin is put in a uncomfortably close hot seat in front of master xi. 
Then just listen to the conversation and watch his body language. Putin is middle management trying to explain to the boss that he can fix this. 
Putin delayed his invasion until after the closing ceremonies of Xi’s Olympics which put him squarely into the rasputita mud and cost him his quick victory over kyiv. 
The only reason anyone who knows Russian mud would do that is out of necessity.  
Xi is the king shit.  Putin is a thug for hire.  Way too much of this war makes no strategic or tactical sense.  Putin certainly doesn’t care so much about John Q average Russian in the donbas that he is willing to throw a million more Russians at it with no supplies or ammo.  
Putin fucked up.  But xi is the shot caller >

If he's seated too close to Xi it's a "hot seat" if he's seated too far away it's allies trying to distance themselves from him. The mental gymnastics of you people... >

Are you arguing there isn’t a reasonable distance for two people to sit from each other? Too far and too close can both be valid comments depending on how extreme it is. Surely we can agree 3 inches nose to nose and one football field would be equally mental, no? >

I'm arguing that you are coping and to take a break from reddit. >

“Ya know, I’d love to but I’m neck deep in a genocide, a runaway pandemic and I’m planning my invasion of Taiwan. I’m just swamped.” >

To the pain? >

I appreciate the balls. >

Xi will decline >

Yeah work with another dictator who tortured his own people for nothing more than a red mark on an app. >

China is sus >

Honestly if Xi were smart he'd agree to this visit and slowly start shifting allegiance away from Russia now that it's clear how hollow the Russian state capacity actually is. He probably won't though, because he's an authoritarian douche and Russia is just about the only country with any kind of weight that's willing to join an anti-democratic axis with China. >

But Xi meeting with Z would not be a slow start to a shift like that. >

A great move that costs them nothing and makes Xi look like a weak russian puppet rather than a global leader if he declines. >

Good way to make China look like a bunch of assholes if they don't agree though lol >

*China's Leader
There, fixed it for you. He's called 主席, or "Chairman" in Chinese, not president, which is 總統. Leader is more neutral than Chairman, as it evokes thoughts of Mao Zedong. >

His official position is chairman of the CCP as well as president of China. You aren't fixing anything if it's not broken :/ >

I thought we just want to align and cooperate with true democrats? >

China will nope out. >

I adore Zelensky but sorry this is not going to happen >

This is a great tactic. Let's see if Xi accepts the invitation? In person would be the best. Imagine the look on puti's face? >

Now it gets interesting… >

China who somewhat openly supported Russia was to be expected.  However, when Russia stunded the world with shear incompetence on the battlefield, China benefited.  Xi is now looking at how he will leverage a failed state (Russia) Regardless of the outcome of the war.  The unprecedented sanctions will cause a collapse of the Russian economy and will cause Putin to cut deals Xi. >

IMO a shift in Xi's stance is likelier than you think. Reportedly Xi has a boner for the macho-dictator and believe autocracies perform more efficiently than democracies. That image is quickly fading on the ground. After all Xi is a pragmatist, if you look at how he reversed the zero-covid policy. >

eh, don’t waste time with them. How about more dialogue with Taiwan? After all, they’ve done a lot more to help Ukraine.