I googled "PT interview questions" and went from there. If you can find posts about that school's specific interview questions, jackpot. Otherwise, prepare natural but concise answers to the general questions you'll likely be asked (tell me about yourself, why did you choose PT, current events in the profession, etc.). Read up on the APTA and current issues facing the profession. I also recommend looking up the professors in your program and looking at their interests/research. Come with questions about their work. Practice answering questions when you're driving around by yourself. Google the STAR method for interview question answers and start thinking of stories to tell (times you had an ethical dilemma, had to tell someone bad news, failed at something, overcame adversity, etc.) Have questions that you actually care about the answers to, not just ones you think they want to hear.
Finally, take a deep breath and be yourself! It's easier said than done but everyone will be welcoming and genuinely excited to speak with you on interview day, so don't let your nerves get the best of you.