If you're asking if being in JrROTC helps in the "Application process" for applying for an academy appointment? Yes, it does. Just as much as being in the school band, president of the spanish club, football team, volunteering for meals on wheels, etc... You don't get extra/special points on your application because you were in JrROTC or Civil Air Patrol or Boy Scouts, etc... The academy is looking for well rounded individuals; which included extra curricular activities and leadership positions within these when possible. So yet, JrROTC helps. just like the other 1436 other types of activities you could be involved in. Do the activities you like; and excel in those activities. That's what matters... Not the activity itself.
If you're asking if any JrROTC training will help you in your Basic Cadet Training or being at the academy as a cadet; the answer is "Maybe". That totally depends on you. There are plenty of Top-10 cadets in each class that NEVER had any JrROTC, CAP, or Scouting involvement. There are some that did have such involvement. And there's some who are ranked #600 out of #1200 who were high ranking JrROTC or CAP members. Depends on you, the individual. Are there any similarities between JrROTC and the academy? Yes; they both wear uniforms. There's some drill and ceremony procedures that are similar. There is a rank structure. That's about it.
Bottom line is: It shouldn't matter if JrROTC will help at the academy or not. You are doing JrROTC because you LIKE IT, and are PASSIONATE about it; or you're doing it to PAD YOUR ACADEMIC RESUME. Only you know the answer to that. Hopefully you're doing it because you really like it. Same with the person who is the drum major in the band; the person involved in the Art history Club; the captain of the basketball team; or the person who does fund raisers all year for "Toys for Tots". best of luck to you. mike....