Depends on stuff like the EU, which featured the occasional survivors of Order 66. The Conclave on Kessel
tried (and failed) to kill Vader with an ambush, and Empatojayos Brand
survived the purge with grievous wounds and was still alive after the Emperor's death at Endor.
I don't watch CW, so I have no clue if there's any official word in there to the effect that only Kenobi and Yoda survived. Going only by the movies, one could assume that since they're the only key Jedi shown afterwards, but a lot of the tie-in material suggests there were others.