Is there a way to directly donate to support a comic / light novel / animation? In many times we are viewing a story without paying. It can be an animation broadcast on television. It can be comic or light novel that is only translated by volunteer online and one is forced to view the pirated version as this is the only way to view it. So there should be times we feel that want to have some ways to pay some money back to support the comic / light novel writer or the animation company. 

Currently the most common way to do so is to buy some products, like Blu-Ray Disk, poster, figures, toys and video games etc. However, when the comic / novel / animation is so rare that you are forced to view a pirated version, it usually means it is also impossible to buy these products.  Even if it is possible, it feels odd to buy unnecessary stuff just to show my support. Sometimes it is just not environmentally friendly, and sometimes (think of Strike Witches) you really need to be brave enough to just possess the product itself. 

Then I think of the donation page or the "Buy me a beer" button in many free software site (like this one). So I am thinking if there are similar things for ACGN (Anime, Comic, Games, light Novel)?
Simple answer is no. Anime are created through production committees. How they come about can vary. The best way to support a commercial work is to purchase the principal media (discs) behind them or the source material (novels, manga). 

The crowd funding, Patreon-type model is not very well-known or accepted in Japan, but they do exist. The most notable recent one is Nekopara. However, these happen fairly infrequently, and typically only happen for smaller or self-published work instead of bigger IPs from established.