GTA 6 will tie earning money directly to the progression of certain main story missions. At certain stages, players will need to earn income within the game world before they can continue with the mission; selling stolen cars or robbing locations are viable ways to make money.
Rob Nelson, co-head of Rockstar North, stated in an interview with IGN that the team wants money to carry more weight in this installment's story than in previous GTA titles. This means that in some missions, the funds on hand will determine whether players can progress, rather than just affecting what they can buy.
Nelson did not specify how many times such stages will occur, how much money will be required each time, or list all the available money-making methods. How these earning requirements will impact the pacing of actual gameplay remains to be seen once the game is released.