The Ruin DLC most likely happens in 2032, two years after Security Breach, which means that if Gregory stayed in the fire, even if he hadn't been burned, he wouldn't have survived due to lack of food and water. Something else to highlight is at the end of the game, in which Gregory tells us that he managed to escape with Freddy, since he says that a friend of his opened the way for Cassie so that I managed to escape, and you already know that there are different endings in Security Breach, but there are only 2 that match what happens in Ruin. Those 2 endings are Burntrap's and the van's, but we don't know how Vanessa managed to escape, the most likely is Burntrap's, since in the end it catches fire and we don't know what happens next, but it is very likely that Gregory and Freddy will manage to escape. The Freddy seen in the Gameplay is not the one we met in Security Breach, but rather a Prototype, as it says on his leg, therefore Freddy managed to escape, but without first having opened an emergency exit in case someone had been trapped. So Freddy and Gregory escaped safely from the ruined Pizzaplex. Another thing to note is The Mimic. Burntrap is not The Mimic, I know this because his shape is not the same, his height doesn't match and in the Scooper Ending, The Mimic wears a lion costume, unlike Burntrap, who wears a bunny costume, so Burntrap is most likely the last time we see Afton, and the new Bonnie of the AR world, according to the subtitles, is female, so it may be the digitization of Vanny's consciousness.

That's my theory, thanks.