he looks tiny, corns can get into very very small places, and through very small gaps. I remember seeing mine having a right little journey along the top edge of my wardrobe after he got out of a seemingly tight viv.
there's already some good advice here... to add to it, make some traps - 2 litre bottle; cut the top quarter off where the spout is and then insert this back into the bottom of the bottle the other way around. dont leave any sharp edges! tape it up so that it's easy to remove without getting anything stuck.
stick a pinky (or whatever he's feeding on) in the bottle and leave it in a warm dark place. he will be able to get in the bottle easily enough but getting back out will be more tricky, and if he does go back out you will know if he's been there as the food will be gone.
That works for some snake escapes, but we lost our boa and after a couple of month there is still no sign of him

they can survive for ages without food though.
put plenty of water bowls out, and even et up a little floor level home with a basic heat-mat, water and food items when you can. I've no doubt he will be in the smallest, darkest, warmest, tightest place in the house! check behind every heat source in the house!!
if he does come out it's likely to be in the dead of night, when no one is around. less likely to be during the day, but he may suprise you when you're watching telly!