Dude, I'm aware it's a drawing. But seriously, there is no such thing as a stomach that can expand at such impossible sizes, okay? You need to think logically here. Real or not, that stomach would be bursted.
And you are 100% correct Most stomaches can reach about 1 liter (0.26 gallon) but if really pushed it can reach to 4 liters (an entire gallon) on food If beyond that, its automatic bursting unless your some type of super human designed for making the earth overpopulated