Is there such thing as morality in “survival” mode? Is a human truly capable of discerning and acting upon “right & wrong” when enduring great suffering?

There is definitely a survival mode. Elie must "turn himself off" to emotionally endure the suffering. He knows right and wrong but these ideas vanish in the haze that is a Nazi death camp. When people are treated like animals, right and wrong become merely distant ideas from a past life rather than reality inside the camp. Surviving minute to minute is Elie's only concern.