Officers who graduated from service academies or received ROTC scholarships do qualify for Post-9/11 GI Bill (Chapter 33). However, time spent satisfying the ROTC/Service Academy active duty obligation does not count toward the active duty service necessary to qualify for the benefits.
These requirements are typically 5 years for academies and 4 years for ROTC grads. For example if an ROTC grad served 6 years after graduating college, their first 4 years would not count but their subsequent 2 years of service would qualify that office for 80% of the Post-9/11 GI Bill.
If an ROTC graduate becomes a reserve officer and then is activated on federal orders it is possible that this active duty service would qualify for Post-9/11 eligibility.