I’ve hatched a few eggs, mostly 5k eggs and some 2k eggs. I believe when you hatch a 5k egg you get 10 candies for that Pokémon. Although, I’ve looked back on a few Pokémon I’ve hatched from 5k eggs and found more than 10 candies. I wasn’t really paying attention when I hatched my few 2k eggs, so I don’t remember how many candies I got.
How many candies do you get for a 2k, 5k and 10k egg? And does it vary with the Pokémon that you hatch, or which incubator you use (infinite or limited)?
2 km eggs: 5 to 15 candy 5 km eggs: 10 to 21 candy 10 km eggs: 16 to 32 candy
Here is a Reddit Link supporting this claim.
(There was a single report of 4 candy from a 2 km egg but I’m guessing that was a typo/error.)