So, I ended up stumbling across a borderline exploit that worked remarkably well for this: As soon as you finish talking to Romero, run downhill, away from the gates, to the Mausoleum (where the tunnel to the Nosferatu warrens is), and run behind the Mausoleum.
Chill out there, kill any Zombies that happen to find you, and wait until the clock is down to around 1:20 or so.
At about 1:20, run up to the lower gate and kill the zombies attacking it.
Hold them off and keep them under control until the clock runs out.
The upper gateway will remain safe through all of this and if you can keep the lower gate under control for about a minute, you'll win.
gaming.stackexchange.com/users/3129/LessPop_MoreFizz
It is possible to do so
but it's very difficult.
Try to target zombies that spawn near the gates, "auspex" should help indicate which ones are a priority.
I found melee weapons worked better for me than guns.
Don't let any of them get close to you however, if they grab you
it takes too long to shrug them off.
Do you particularly want to do this quest?
The alternative "Pimpin for Romero" is a lot easier.
gaming.stackexchange.com/users/5762/getthatcrate
I guess I got lucky because I didn't have any problem with the quest.
I had a rifle and took up a post between the two gates, running back and forth as needed to make the trickier shots.
Of course I had pumped a fair number of skill points into firearms and such that that made it possible for me to get through it without celerity.
gaming.stackexchange.com/users/451/Phileosophos
Hey all I just finished this up after looking for advice on this myself
and I finished it legit without too many issues although it did take a couple tries.
You'll need level 5 Thaumathurgy.
I had the "Infernal" background which made Thaumaturgy cheaper
but I also had a ton of xp by this point
so it doesn't seem like that wild of a requirement.
So basically the idea is to just focus on the zombies at the gates and switch back and forth frequently, using the zombies between the two gates to refill your blood bar using Blood Theft and Blood Strike.
Blood Boil:
This is going to be your go-to once things start heating up.
It will often not kill all the zombies at the gate but doing damage to them will get them to stop attacking the gate long enough for you to clean up.
I used an axe.
Blood Theft/Strike
: Use this on zombies as you run between points.
There's a long time between activating Blood Theft and getting the return so make sure you fire ahead of you as you're running otherwise
I found myself sometimes not getting the blood return that I was expecting.
Other than that don't worry about killing any zombies other than what's attacking the gates.
Once you kill a pack of zombies at one gate just run for the other even if it looks like something is shambling toward the gate you just cleared; maybe slap a Blood Theft on them and keep running.
It took me a few tries but it ultimately wasn't too hard at all.
The biggest things that tripped me up were trying to play prevent defense instead of just floating between the two gates.
Unofficial Patch 9.6
gaming.stackexchange.com/users/163818/anathema
I just beat it as a Tremere, and it was incredibly difficult.
For most of it, I used a pistol, walking up close to each zombie allowing me to pop them in the head, which is a 1-hit kill no matter your firearms skill.
At about 1:30 left, things started to get crazy and I ended up having to run back and forth between gates casting Boil blood twice (One cast will not kill all of the zombies).
Obviously, I had to chug a few blood packs while I made my way to the other gate to repeat this process.
gaming.stackexchange.com/users/43541/user43541
It can only be finished with either good firearms (e.g. steyr gun or a sniper rifle and guns at 7 at least) or celerity at 5 (maybe 4) and melee/brawl and possibly with thaumaturgy (mainly blood boil) or other mass spell
(but it would be extremely difficult).
Unofficial patch has decreased the difficulty significantly.
Check the 1.2 version or 1.02 and see for yourself.
gaming.stackexchange.com/users/146768/Kirika Tokihashi
The fire axe is your friend.
Or any other high damage melee weapon for that matter.
I have never used firearms in this mission, they're slow and you have to hit the zombies in the head
so use a melee weapon you can hit several zombies at once with instead.
What you do is run between the two gates killing only the zombies near the gates, don't bother with the rest.
You kill the zombies at each gate maybe 3 or 4 times then you're done.
I don't even have celerity
gaming.stackexchange.com/users/70256/Jim
Actual bypass for this mission, is run to the left side of the Mausoleum (when looking at the Mausoleum stay left side) and stay at the back left wall behind the little crypts.
I just had to kill 2 zombies and wait the 5 mins in the corner.
gaming.stackexchange.com/users/219046/levi
Is the quest "You Only Die Once a Night" even possible without Celerity? I'm running back and forth between the two gates, and no matter how fast I blast these Zombies heads off, I'm just wasting too much time going back and forth, and they're making it out of the cemetery around the 2 minute mark every time?  I'm playing as a Tremere, so Celerity is off the table as an option. Running Community Patch 7.3 if that's relevant.
Completing "You Only Die Once a Night" without Celerity?
gaming.stackexchange.com
<vampire-the-masquerade-bloodlines>
gaming.stackexchange.com/questions/17369
gaming.stackexchange.com/users/3129/LessPop_MoreFizz
Melee weapons work better than guns to hit several zombies at once. While many are facing problems with this mission, the use of melee weapons seems to make this mission a lot easier.
The community implies that there is an increased difficulty if firearms are used or being underpowered. The best choice seems to be melee weapons.