Question: We could see that Theon Greyjoy helped Sansa Stark escape from Winterfell which was under Ramsay's control by jumping off the wall. The outer wall is said to be about 80 feet high. How did both of them survive jumping from that height? It is highly unlikely to survive that jump even if there was snow.

Answer: 
If the snow's deep enough, they could easily survive a fall of 80 feet, regardless of plot armor. 

[This video](https://www.youtube.com/embed/-RYkapHBVs8) shows a guy skiing away from a jump off a 255 foot cliff. He lands head first.
There may have been some water in a moat that's frozen over, so they hit the snow then they hit they hit water too slowing their fall. Would have been very wet though.