During the beginning arc of Boruto, Sumire tries to carry on the will of her father by trying to destroy Konoha with Nue, She used the "cute scary" beast to feed on people's chakra and negative emotions, but was later on discovered by Boruto and his friends. After Boruto defeated Nue and escaped from "Nue's dimension", we see the summoning mark vanish, and I initially thought Nue died but apparently he didn't.
My questions are as follows: how was nue able to survive?
how does the mark reappear on Sumire's hand if Nue technically died? Also, Does Nue have size limitation due to the decrease in the summoning mark?