I've never read it. But heres what I found on the internet for it.
Wiesel had to grow up quickly, struggling to understand himself, his situation and his religion, the very faith that thrust him into the middle of the Holocaust. Night explores how the loss of family and identity can lead to questioning of faith, and how horrific situations can push children into adulthood.
Survivor's Guilt is the condition of feeling guilty after surviving a situation in which other people died or were harmed in. You feel as if you could've saved someone or some something different.