Yikes! My only experience with tortoises is watching the wild ones that visit my yard and watching Garden State Tortoise and a couple of others. I have no idea how to find him, other than letting your neighbors know to watch for him and maybe even putting up some posters, like is done for dogs if he isn’t found in another day or so. Letting the local wildlife rehabbers and humane societies know might also help. Even though most don’t take reptiles, it’s possible someone who might find him would try to take him to a humane society. I would imagine he would be staying in the more hidden underbrush, but also looking for tasty wild greens. If he has a favorite food, you could try making a trail of sorts leading back to your house. While he actually could have gone quite a distance, it’s very possible that he has pretty much stayed near home. Obviously, be sure to check well beneath every bush, plant, tree, porch, in long grass, etc. If watching all the tortoise/turtle channels has taught me anything, it’s that they know how to blend in to their surroundings very well. Sending lots of good vibes and prayers that you find him quickly.
