Latest report is that 260 were evacuated from the Azovstal steelworks, 53 with serious injuries, the others less injured. Estimates vary but it is claimed only a few hundred remain at the plant but they will be removed in the next few days. All are going to Russian held parts of Ukraine as prisoners of war. The Ukrainians claim to hold about a thousand Russian prisoners and are hoping a swap can be arranged.
https://www.youtube.com/watch?v=hHryfoPZ-Vg
I don't know what the deciding factor was that made them decide to give up now. They must have known for some time that rescue was not going to happen. Some efforts were made to resupply them but they failed. Food and ammo might have just run out. But they have achieved their objective; they kept thousands of Russians tied up for weeks, giving the rest of the Ukrainian army time to stock up on hardware from the west. These troops were the Azov battalion and part of the reason they held out so long is said to be that they suspected that the Russians would not accept surrender and shoot them regardless.
This could give Putin the "off ramp" that I hope he is looking for. He can claim to have finally captured the Nazis that he went there to get so now they can all go home. Won't happen of course but nice if it did.