Not quite. The 4th Edition GSL did push Paizo into doing what they were already planning on doing, create their own Pathfinder game. And it was a very successful game. However, Pathfinder sales didn't eclipse D&D sales until AFTER 4th Edition stopped publication and WotC wasn't producing ANY D&D content for a while. As soon as they started up with 5th Edition, Pathfinder slipped back down to second place.
Still, your point stands . . . WotC's open license shenanigans during the 4th Edition probably did have a lot to do with making Pathfinder the success it was. And their current shenanigans with the new "OGL" is already pushing publishers to create their own systems and new, truly open, licenses. The situation isn't identical, but history does seem to be repeating itself . . . .