I actually have thought quite a bit about the timing. In fact, there are two components regarding the timing. First, there is where the jet was along the flight path at a given moment. Second, there is when DBC actually jumped.
I ultimately felt comfortable that the first point regarding the location of the jet along the flight path (irrespective of the path) was probably accurate. In other words, the FBI stating that the jet turned at Malay at 7:59 strikes me as legit. After all, there aren't too many ways to screw this up.
On the second point regarding when DBC jumped, I likewise felt it was likely that he jumped when they felt the "pressure bump." Also, that this time was probably 8:12 or very close to that time.
Of course, both of these assumptions on my part--and the FBI--may be wrong.
Needless to say, the previous assumptions, along with other factors, cause me to believe that DBC almost certainly survived. In fact, I would put the odds at close to 100%.
Of course, none of these things can be known with absolute certainty. What can? That said, if the "absolute certainty" standard is applied too rigorously it's inevitable that paralysis will set in and nothing will get resolved.