All the London railway stations :
I visited Archway station on the Northern line in June 2019, and the station is seriously NOT accessible. There is an escalator, and then 20 steps to exit from the southern or northen bound trains.
Archway Station stairs (20) to exit station
Archway is not an accessible public transport station for wheelchair accessibility due to the stairs and elevators to platforms.
Underground lines : Northern
Accessibility friendly : Not accessible to wheelchair users due to stairs (20 steps) and elevators between street and platforms.