Does Umass Amherst allow deferrals for a year to take a Gap Year if I make a strong case?
I don’t think so. I believe that you either accept their admissions offer, or you have to decline it and reapply.
If you have a good reason to take a gap year, then you should ask admissions at the university. Just call them or send email and ask.
Many schools allow gap years. All you need to do is contact admissions and ask.
And many schools do not allow gap years. The only way to know is contact UMass.
UMass Amherst doesn’t allow you to defer your admissions. You’d need to reapply for the term you’re planning to enter:
https://www.umass.edu/admissions/deferrals-policy