Your hours play a small role. When applying for a pilot slot in the Air Force, you will have to take the TBAS and the AFOQT, two different standardized tests. Then they will take your flight hours, and put the three criteria in a secret formula. You will get a score out of 100 that is factored into your overall pilot application package, this score is called the PCSM.
Does getting a 100 mean you will become a pilot? No, they look at other factors as well, especially in the Guard. Does getting a low score mean that you won't become a pilot? Not necessarily, I have known people who had a score of 6 and still got a pilot slot. They look at you as an overall person.
How do hours help? Well, if you do ok on the AFOQT and TBAS, with 0 hours you may have a score of 50. If you add hours, 1-10 hours may boost your score to a 71. 11-40 may boost it up to 81. 40-100 may boost it to 85. 101-150 may boost it to 87, and 200+ hours may boost your score to a 91. This is not 100% accurate, since the formula is a secret to me.
Now, in AFROTC, this score only accounted for 15% of your overall pilot package, so to speak. I don't think they care about the score at the academy, and I don't know about OTS/Guard slots. If you go to wantscheck.com, you will see that people post their PCSM score, but also their GPA and other information. I know in the guard, the interview is an extremely important factor. I have known people who got hired at guard units and didn't know anybody, but these people applied, went to the interview, and blew the panel away. Most of the times, you need to know somebody from inside, but they are always looking for the most qualified candidate.
So yes, hours do count, but not that much. Sometimes, it is the fact that you took the initiative to start flight training on your own is enough to show a genuine interest. What is important to remember, is don't walk in and think you are some sierra hotel pilot because you've got an instructor certificate. The ratings themselves won't do so much for your application, to my knowledge. If and once you get to go to UPT, don't advertise your ratings. They will expect you to learn "the Air Force way" and treat you as if you have never flown before. You will even be required to do the 20 hour IFS (introductory flight screening) which is in a Diamond Eclispse, regardless of what rating or how many hours you hold.
Best of luck