Unless you do something amazing during your gap year that makes you a much more desireable candidate, I just don’t see it. If you reapply your chances while slim are not 0 vs not reapplying. But separately, you need to ask yourself why the obsession with Harvard. It sounds like you have other great options in hand. As you move on in life, there will be a lot of things that don’t break your way. You have to learn to accept and adapt to those situations or it will be difficult to be happy and well adjusted.