All the London railway stations :
Underground lines : Victoria, National Rail Greater Anglia
Accessibility friendly : No part of Seven Sisters station is accessible on
the Victoria line or on National Rail to wheelchair users.
The Victoria line is 19 steps and an escalator between the booking hall and the platforms.
Depending on which entrance is the number of steps from the booking hall to street level. :
Seven Sisters Road is at the same level, no steps.
Broad Lane exit is 33 steps
Earlsmead Road exit is 31 steps
West Green Road exit is 33 steps.
National Rail lines there are stairs to platform 1, or stairs and an escalator to platform 2.
General description : See wiki
More comment : National Rail map & guide