A rough outline:
Bad interview: Rejection regardless of stats.
Mediocre interview (where most people are): Stats determine who gets in.
Great interview, great stats: Acceptance.
Great interview, bad stats: On the fence, depends on how bad the stats are. If stats are really bad, worst case will be waitlist. (I rule out rejections because if they were going to reject you regardless of how great your interview went, they wouldn't interview you in the first place).
I don't know a single school that doesn't look at the "entire package" before making a decision. If you know of a school that claims to not look at anything but the interview before making their decision, please let me know so I can make them my top choice (I am very much so against this entire process being a stats-war). Most schools use a point system, where your GPA and MCAT get an objective # of points assigned. Then, there's a reviewer 'subjective' section where they judge you based on the 'feel' they get from you (I think this is based on secondary essays, extra curriculars, recommendations, etc.) Lastly, there's interview points. I think this is the way they do acceptances, not interviews. I think interviews are mostly subjective. This is mostly speculation based on rough outlines I've been given by different admissions directors on the process they use.
I spoke to the Associate Director of Admissions at Duke yesterday and he told me that they don't even look at recommendations pre-interview. Presumably, at Duke, the recommendations are read right before making their decision -- take that for what it's worth in relation to how much the interview weighs in on things.