There is a shuttle bus (with a restricted service) from Sermizelle-
Vézelay station to
Vézelay. Details
here.
You do not say which day you are travelling, but, assuming it is a weekday, if you take the 16:27 train from Paris-Bercy station, (close to Gare de Lyon) you will arrive at Sermizelle-
Vézelay station at 19:08 but you will then have a wait of 1 hour to catch the 20:08 bus to
Vézelay, arriving at 20:23.
You can get a price for a taxi, and book online, here.
For more information, look here. (In French)
Good luck!