Do GTA 5 saves back-up to a cloud service?
Solution 1:
The save files do not get backed up to cloud services, on steam or on RGSC versions of the game, you have to backup and restore them yourself.
The save files are located in C:\Users\USERNAME-HERE\Documents\Rockstar Games\GTA V\Profiles
.
Solution 2:
Since August 3, 2017, Story Mode Saved Games can be backed up to the Rockstar Cloud. This option can be disabled from the Rockstar Game Launcher settings in a per-game basis: