I think there's an old topic about that as well. He wound up getting capped while waiting for a companion (both were carrying false papers and in disguise, to attempt to walk out to the western allied forces), was found dead at the rendezvous, and I forget, the companion had to help bury Bormann and some others. Years on, he was tasked with finding the location, and the remains were dug up. I've seen a photo of the skull, definitely his (kinda weird lookin' head on that guy). There's been an undercurrent that Bormann was a Soviet mole and was the person evac'd from The Bunker after the fall of Berlin (a single figure, trenchcoat, hat, dark glasses, emerged from the lair and waiting an hour or so out front. Red Army crews cleared the debris from the street, and were followed by a staff car, into which the mole was ushered), but the Bormann family rejects the entire notion, accepts the official account of his death.
Can't imagine Hitler, with Braun and party in tow, could possibly have made it out.
More important, what would be his motive? Hitler and his inner circle knew from 1944 if not 1943 that this was a fight to the death. Given what they had perpetrated with the Holocaust, capture would inevitably lead to an ignominious death. Maybe Bormann thought he could somehow cheat his fate, but Hitler knew he never could once Berlin had fallen.