I've waited 24 hours in game, 5 times, and the tutor and other students still haven't shown up outside of Saarthal. The only one that showed up is some elf girl in blue robes who was with me and the others in the College.

How long do you have to wait for them to come? Or did they get killed and I have to go back to a previous save? I tried going back to the college but they weren't there either.

It should only take 2 or 3 hours. Where are you waiting? There should be an quest arrow near the door. Don't wait on the platform where you get the you have discovered Saarthal message.

Everyone is under Saarthal.

First off... You dont need the students to gain access. Just the old dude. And hes most likely been held up by some frost trolls or something. It happens. Either reload an older save or go looking for em. I dont believe the old dude can be killed so you good there.

Look along the path from the college to saarthal, first time around I followed them and we got ambushed by trolls and bears.