I think he is proabably dead but... I am a bit suspicious about how ambiguous her words to him at the grave were. You could take all the stuff about "I miss you", !I wish you could have been there" "the doctor says I was calling for you" either way- dead or just not around i.e. still on the island.

But Jack did say at Kate's trial that there were 8 survivors but 2 died. I know everything he said to the court was a lie but I took him to mean that 8 of them attempted to leave the island. 2 of them died (Jin- possibly being one of them) and 6 are alive and successfully rescued- Kate, Aaron, Sayid, Hurley, Jack and Sun.

So I guess next week we find out who the other one was that died. I just hope it isn't Sawyer! Prob not as he was always so determined that he would stay behind. Possibly Desmond?