My question is whether I will get the benefits of the "Criminal Enterprise Starter Pack" or the benefits of linking my Social Club account to my Twitch Prime account again when I start a new game and delete the old one. I already received both of these packs on my first GTA online savegame, unfortunately I invested incorrectly in the distribution of the money. You can create a new character but as far as I know both characters use the same balance. Then it would make no sense to be able to bag the rewards for every character.
So I don't know about Twitch Prime, but you'll keep the benefits of the Criminal Enterprise Starterpack. Only for the $ 1 million I'm not sure if you've already spent it, but e.g. You can buy the real estate again free of charge.
