I don't know if there is, but I know that there is a reference to his mother in the secret mission in GTA V, but I was wondering if C.J. is referenced at all in the game?
Other than a carefully placed Easter egg, there's no reference to C.J. at all, this is because GTA V is in HD era while San Andreas was in the 3D era. According to @CaulynDarr the only character that has appeared in both GTA: SA and GTA V is Lazlow. He is in all the games.
The old PS2 games (GTA3 through San Andreas) and the current generation titles exist in separate continuities. Outside of possible Easter eggs there probably won't be any direct appearances. Except for Lazlow. He's in all the games.
The Easter egg spoken of is with reference to the Sweet & Kendl mission of GTA San Andreas, which featured CJ, Big Smoke, and Sweet riding bikes down Grove Street.
During the mission Hood Safari, while on your way to the location, you can see the characters riding their bikes down Grove Street as you approach. It's not actually them, but it is a reference to them and that mission.
Here is the Wikis description of the event:
As the player approaches the cul-de-sac, occasionally they will be able to see 3 men on BMX bikes riding down Grove Street. The three men are dressed to resemble Carl Johnson, Big Smoke and Ryder. This is likely an easter egg, referencing the mission Sweet & Kendl in GTA San Andreas, in which CJ, Big Smoke and Ryder escape the pursuing Ballas on bikes.
Here is a video that shows the GTA V scene and the GTA San Andreas scene: