My endoscopy results came in, and they say I have moderate chronic gastritis, would this affect my surgery in any way?

You will have to consult with your surgeon, as I suspect that the answer to this question might vary based upon the surgeon. If I had to guess, I'd suspect the surgeon would prefer to treat the gastritis before the surgery and verify that it is resolved with repeat endoscopy. Please let us know what your surgeon says!

I guess it didn't matter because he set my surgery date for next Tuesday.

Well good luck and best wishes on your surgery.. I hope everything turns out ok..