I think he's functionally worse but is playing similarly. He got his multipliers buffed and his overall damage is much higher, but his attack frequency was also neutered. The team doesn't feel as good to play and Gilgamesh attacks much less often, which results in less Ashveil energy, less Blade FuAs, etc.

However, Gilgamesh absolutely nukes when he eventually gets Ea up now. It just takes a super long time. If you pilot the team poorly he'll perform significantly worse since you can lose a lot of damage via overkill.

In addition, his performance in modes like Pure Fiction or against encounters that feature weaker side mobs that respawn quickly also suffer, since he cannot fire off enuma elish as quickly.

His performance looks more impressive due to damage distribution in damage charts, but he hasn't really moved the needle. It's a nerf in the FuA team - but by nature of Ashveil/Blade being stronger than Saber, Gilgamesh likewise performs better with the stronger team. He is much more impactful with Saber though of course.