Everywhere on Disney property that I have eaten with DS who has an allergy has offered gluten free options. Sometimes they are very limited. Maybe look at menus that you are interested in.
Sometimes it may have what options are available on the menu itself. If not, I have found it helpful to either look up dining reviews on the forums for that restaurant or as shocker suggested, use a gluten free app. The last one I used had information that was a few years old on some restaurants, but was still helpful. I looked for gluten free disney on the App Store.
We have eaten at T-Rex, rainforest cafe, planet Hollywood, d-lux burger and blaze pizza with things that my ds was happy with. I have read great reviews for the huge menu at splitsville. When we tried raglan road, my ds wasn’t hungry, and he doesn’t like fried food, but I thought the food was great as well. Don’t forget to look at Erin Mckennas Bakery too. It has great snack stuff.