Suicide, capture, and trial
IIRC, it was Stalin that wanted trials for the nazi's captured. So, whoever captures him, I'd expect the brass would want him alive. However, I expect that the report of his capture describes him as resisting, so it was needful to shoot him...many times.
As for suicide, it takes only a moment--but it's one thing to prepare to comit suicide as things come apart--and another all together to go from the mentality of "evade capture" to deciding to kill oneself. He might decide too late. Alternatively, if he was wounded in an escape attempt, he might be unable to do anything.
So, I seeit as possible for an escaping Hitler to be captured rather than killed--but unlikely. Just my quick thoughts; I'm no expert in this area of space-time.