I think beyond population is:
1. Quality of HS programs in the state, and
2. Fervor for football in the state.
New York is not a hotbed for football recruits. Georgia is, not only because of population, but because of enthusiasm for the sport which means money going into HS coffers which means better programs and training.
I'd guess nearly every top Ohio HS player dreams of playing at OSU (some ND). OSU is dominant for a reason. I don't think Clemson has "staying power" because of these factors.