Hello there!
So, Yeah, gamepad control It's actually possible. Specifically, on the case on "event" inputs - that are mapped on the default "Ok" RMMV - it's pretty easy if you use plugins' like "GamepadConfig.js".
On the other hand, if you're talking about model rotation and such, this would be a little different. As default, the Babylon's view is attached to mouse control (from BabylonJS API). You have two approaches :
1. Use the default Rpg Maker MV input's class combining them with Babylon JS camera's control.
2. Using the "Gamepad Manager" API from Babylon JS.
However, if the gamepad's feature is a requested feature, when I'll have some time I'll try to do a plugin update supporting it!