At this point, how do we know they’re even alive?
We really don't, do we? Aside from John Kerry's report that at least one is still alive.
That's if you trust Kerry to tell the truth, of course.
Most of the people involved were probably CIA, CIA contractors and other security people. Most (if not all) reportedly came from the "CIA Annex", after all.
If everything had been kosher, I presume that State and CIA officials would have made representations to the Senate and House Intelligence Committees straightforwardly explaining the whys and wherefores of their presence and what had happened to them. Thus, there would've been no need to interview the survivors.
The fact that such representations were not made is instructive in itself. Something was going on in Benghazi that shouldn't have been going on. And the administration is determined that nobody's going to find out about it.
If I am not mistaken, whatever it was was a John Brennan operation. As I recall, this came out in association with Petraeus' resignation.
So, not only is the President and the Secretary of State directly implicated in the affair, so is the current Director of the CIA.