Nobody has extremely good data about this because it's in their interest to make that as opaque as possible, but the reporting I've seen suggests that it is, if not the majority at least an extremely large fraction of their customers which are selling AI services, and even where it's used for in-house software development that is largely bankrolled by VC hoping to gain a competitive advantage with AI. It doesn't really appear that the API pricing offers better cost/productivity than just hiring junior devs (lol).