Sure, there are ways to cause
GLKViewController to crash, ranging from giving it a bad delegate, to swizzling one of its methods and dereferencing a null pointer in the implementation, et cetera.
But doing so is pointless. It wouldn't help you fix a crash that users were seeing unless you happened to randomly choose to recreate precisely that crash, which would be very unlikely. And it certainly won't help you fix a problem that users are reporting that isn't even a crash.
What you probably want to do instead is ship a build with improved error checking and logging around the operations you're doing with the view controller and OpenGL setup. Log what is going on, make sure you're checking any
NSError objects that are filled out, et cetera. Hopefully with such a build (which you may be able to distribute specifically to the users experiencing the problems), you will be able to generate a log that can help lead you down the right path.