How obito survive?

Answer 1

Obito did survive, and it was revealed in chapter 599. The chapter features Obito when he was a kid and how he wanted to tell Rin that he loved her. However, Obito never got the chance. We do not know how Obito survived yet, but it all will be revealed next week. However there are many rumors:
Theory 1: Zetsu found Obito dying, he saved him and attended his wounds. Obito's whole right arm was crushed, so Zetsu used his white substances to repair Obito's arm. Not only Obito's arm, but his whole body. After Obito was healed, he planned to go back, but somehow he must have been brainwashed by Zetsu before leaving, or Obito got the news that Rin died and trained hard to activate his Uchiha power to avenge the world, and create a world where no one will cry infront of graves. Throughout Obito's training he started wearing the ''mask'', and carried on all his schemes as Tobi. Obito had Zetsu's power as well, which changes his form and height. Obito's height would have changed dramatically from 154.2 cm to 175.0 cm. It was around this time that Obito mastered space-time ninjutsu, which is his special technique. Obito is one of the gifted Uchiha who can use the special space-time ninjutsu sharingan. Obito, however did not have all the power he needs with just one eye. Obito and Zetsu were close friends. They were one of the two who know each other the most. It was around this time that Obito led the nine tailed fox attack on the hidden leaf village. Obito fought a destined battle with his mentor Minato. Obito apparently failed his mission, and went away. During the fight with Minato, Obito lost his arm, and went to Zetsu to regenerate it again. Obito at some time went and found Kisame as well, which makes sense to to the part where Kisame knows who Tobi is.