I am not say this was whatt of happened, just posting the theory out there that his stood and faced Viscereon to distract it from Arya.
He may not have, and we probbably won't know unless it'a confirmed.
As for how would Jon know she was gonna take him out, Arya and Jon have a connection we have seen since S1 Ep1 and if he saw her racing across (there is a glance to his left atone point) and we must assume during the time prior he will know of her skills at fighting and ruthlessness at killing (little finger) .
For me the win is all on Arya and he is just another factor like milesandre in her achieving her victory.
Also think people have overlooked those months being blind when some were questioning how she could move so stealthly and quickly in the ice storms darkness.
Everything she has done since the start has prepared her for this