I might have misspoke when I only said that the interview was 1/8th or so of your total acceptance. I should have also considered that of the people being interviewed, almost all have high enough GPAs, PCAT scores and extras that no one person will have too much of an advantage over any others. So the deciding factor between the individuals who are accepted to the interview may solely be limited to the interview. Thus, the interview may be 100% of whether or not you get accepted once you are invited for one. That is a scary thought.
Or to simplify....pharmacy schools invite for interviews those that prove they can hack it (i.e. have the grades, PCAT, experience). So, they may be using the interview and essay as a final measure of who to cut.
I personally do not believe this theory. I think that the interview is considered just like everything else. If you have great grades, pcat, extras, experience, then you can probably get away with a mediocre interview. If you do not have those, then you may be fighting for your life in the interview room. Once again, I am not on any admissions committee so I do not know for certain which way it is.