How much space is aloted per game before the cloud storage becomes full? Thanks in advance.

Does it really matter? You still have them on your computer.

I am pretty sure that it depends on the game in question. If a savegame is only a few kb small there really is no reason for Gaalxy to reserve gigabytes of cloud storage and in cease the savegames are quite big it would be wise to reserve a bit more. I cannot tell you how much space for which game is allocated though.