Will a Siemens Q-Type Breaker Fit a GE Type THQL Panel?

Yes, but it doesn't mean you can do it. The GE panel must be UL listed for use with a Siemens breaker, and why would GE do that? You can ignore that fact, many people do, but if a fire starts and the insurance investigator traces it back to that being the cause, you may find yourself with no coverage.