Jin is Dead

As much as I'd like Jin to survive, I'm not sure.

I'd have to rewatch the scene again, but the helo was still pretty close to the ship when it blew up. I am assuming that Sun never took her eyes of Jin. She would have seen him jump if he had.

Also, there were lots of others on that ship, with life preservers, getting ready to jump overboard. If Jin got off the boat, at least some of them would have had to have gotten off as well. Someone riding in the copter would have noticed this and not forgotten about them.

However, let's assume the people on the copter had their eyes closed and didn't see anyone escape. So we've got a bunch of people in the water.

Now let's assume that Daniel finds the survivors. His boat is already full. Maybe he can squeeze one or two more on. The rest would have to just stay in the water and hang on to the boat. Which means they can't really move the boat too fast, if at all.

Assuming they can move the boat, they then still need to find the island or some other land mass. Not an easy task. Meanwhile, the folks still in the water clinging to the boat are becoming snacks for the dharma shark.

In summary, I don't think they can logically save Jin at this point.