As of February 28th, 2021 there are 8,855 levels within 591 episodes, on Android, iOS, Amazon devices, and Facebook versions of the game. You can keep up to date with the number of levels there are, through King’s forums.
Each Wednesday, there are 30, 45, or 60 additional levels added. Sometimes, the forums have polls that you can take part in to help influence how many levels will be added per week, for the next few updates.
Candy Crush Saga is said to be a Saga that never ends, and with new levels constantly being added, it does look like there is no end in sight.