Is your chances higher to get into an elite college by applying through Questbridge?
Yes, in the sense that the admissions process to participate in the College Match is already highly selective, so the colleges that partner with Questbridge know that the students applying through the Match (the students who are selected to rank colleges) are highly qualified. However, every selective college is far from a guarantee, and even with the Questbridge Match program, not all students participating in the Match end up being “matched” with a college, though some will be accepted to a college they didn’t match with during the Regular Decision (ik someone accepted to a HYPSM school RD this way.)
Also, Q offers some good support and their college application has been more detailed, gives you a chance to present more about yourself. But you still need to be the right quality of applicant for the colleges you apply to. In itself, no special bump. But worth exploring.