Is 128GB iPad storage enough for gaming and videos?

Hard to say, will depend on the type of games and length of videos, but just as a comparison,

High end games like Fornite and Call of Duty can be aorund 4 to 5 GB in size to download and can use up for space once installed and being played.

Videos, if recorded in high resolution can also take up around 3 to 5 GBs or more depending on length.

I would say 128GB may be a bit too tight for that.

I would seriously consider the 256 gb version.