At the end of the interview, there will likely be a debrief or an email sent to you with the next steps. Regardless of the outcome, you should receive communication from the program. Again, the timeline may vary from program to program. Some will let you know definitively in a couple of weeks; others may not know for months.
If accepted, you will receive an email and sometimes a phone call congratulating you! The email will reiterate what next steps for confirming your seat will be. Usually, that involves a non-refundable deposit that may range from a few hundred dollars to a couple of thousand dollars. That money is applied to your tuition after starting, but if you decide to go to another program then unfortunately you can’t get it back. There is typically a grace period of anywhere from a week to a month for you to decide.
I interviewed and was accepted much earlier in the cycle than I was expecting; I knew that I was going to PA school before my senior year of undergraduate even started! I got lucky in the fact that I really liked that first program that I was accepted to, so for each subsequent interview, I just had to decide how it compared to that first program. This meant that I generally declined any other seats I was offered aside from the one or two other programs that I liked. After that, I visited those few programs in person to get a better feel for them. After doing that, I could make my final decision.