An interview is not a guaranteed acceptance. I was interviewed at KCUMB which accepts 80% of those interviewed and got rejected! LOL
However, it is a chance -- just be yourself and show the school how much you want to go there. IMO, that is where I went wrong in my KCUMB interview. Initially I had high hopes about the school, but I really didn't like the area (westport) and maybe it showed. Also, MSU was my first choice and I had been accepted the week prior. I was asked a question about multiple acceptances and how I would make my final decision and I didn't really emphasize that KCUMB would be my final decision. Just be honest and make it known that you want to go to that school.