You don't need to accept or decline until May 1 - your appointment has the date you must decide by
Technically, you can accept the appointment and decline it later, but it is best to wait as long as possible
Minimally, it would be considered bad form to accept and then reject an offer of appointment. However, once you reject - that is not a do over if you change your mind
Have to say I am stunned anyone would get this far into the process and ask
'What's the commitment?'
Because I am a grad and my sarcasm skills have been enhanced and refined over the years I feel compelled to ask,
'What have you been thinking about the past many months when applying to at least 2 service academies?'
The minimum commitment is 5 years after graduation assuming you don't fly or choose another career field that requires additional commitment.
Assuming you graduate, you will be commissioned as a regular officer which technically means you will always be subject to recall to active duty
If you are now just getting around to finding out the commitment, don't rush to accept the appointment. I imply from your comment you might be surprised to find out the USAF is expecting you to be committed for the next 9 years of your life (minimally)
Dozens of highly qualified people received the TWE notice yesterday see the USNA forum and had (at least briefly) their dreams crushed. I doubt any that posted didn't know the answer to the 'what's the commitment question'
And to the people that will reply that I am being too harsh on 'just a kid' save your energy