GTA 5 cheat codes do not work in GTA Online as they have been disabled by Rockstar to prevent players from causing mayhem for one another. Pretty obvious really. This also means, no there is no GTA Online money cheat, although on occasion players have discovered some rather inventive workarounds in the past.
It's worth noting that any GTA 5 Cheat Codes that work in single-player have been disabled in GTA 5 Online, with this applying to both the open world and Job segments of the game.
While most Grand Theft Auto games have bittersweet endings, GTA 5 goes in the opposite direction and has a happy ending for everyone involved. This feeling helped to set GTA 5 apart from the rest of the series in a good way.
A lot of people say killing Trevor/Michael was the most realistic option but the guys ordering Franklin to do this used Trevor/Michael and then wanted him dead as he was a loose end.