Hi Deanna!
Thanks for stopping by the Disney Parks Moms Panel with your question - I'm happy to help.
Yes, you will absolutely be able to activate your
Walt Disney World Annual Pass at the International Gateway Entrance at
Epcot. There are
Guest Relations windows located right before the theme park entry point, which will be just a short walk for you as you head into the park from
Disney's Yacht Club Resort. This Guest Relations location is actually one of my favorites, as it typically has smaller lines and a shorter wait than some of the others!
I was able to tackle a ticketing issue on a recent Walt Disney World Resort vacation by visiting the awesome Cast Members at the International Gateway Guest Relations window. Hopefully your experience will be just as smooth, and you'll soon be enjoying the benefits of being a Walt Disney World Passholder!
I hope this helps with your planning - have a magical day! - Diane W.