Two surviving Jedi masters and possibly a third, Shaak Ti was left alive after episode 3 so there could be a final boss for the video game 'Star Wars the Force Unleashed'.
But video games are no longer considered canon.
Any number of surviving jedi are possible, Kanan Jarrus is a major character in Star Wars Rebels which is canon.
Much like any number of surviving Sith, but as all the Jedi and Sith that aren’t Palpatine and Vader are in hiding they don’t really count. And even though Vader and Palp are running the Empire they really aren’t all that Sithie about it, they never seem to be questing after anything or sacking temples, just the occasional force choke or lightning bolts.