I fully expect to see people out on my front lawn with pitchforks and torches after they read what I'm about to say, but here goes, anyway:
I think that - allowing for great simplification, some error and some dramatic license - that the Cameron film has it somewhat right. Captain Smith is shown as decisive at first, then progressively overwhelmed as events unfold. As who in his position would not be? After Andrews had described what would happen, it would have been abundantly clear that the most magnificent ship afloat, costing $7.5 million real and solid 1912 dollars, would be at the bottom of the North Atlantic in less than two hours, with two-thirds of her passengers and crew drowned. It would also have been well within the Captain's consciousness that he himself, above all other persons aboard, was absolutely, fully, unequivocally expected - required - to be among the dead. If anyone thinks Ismay caught Hell for surviving, a live Captain Smith would have been a pariah for the rest of his life, if not imprisoned.
It would have required superhuman strength of character to have avoided becoming overwhelmed under the circumstances. Perhaps Captain Smith did. Perhaps he did not. But if he did, who among us could blame him? One of the horrors of human existence is that human beings are capable of setting events in motion that the human race has no psychic means to deal with.