We have some interesting new information from the GTA Online leaks.

Yesterday, a data sheet indicated that PS5 had the highest average weekly bookings for the game, making 53 % of all bookings. This totaled to $ 4.48 million weekly.
At the time, we did assume that meant most GTA Online players are on PS5, but that may not be the case after all.
PLTytus shared data from DAILY_KPI_METRICS, which revealed that PC actually had the most sold copies of any platform.
From the date of June 14, 2021 to April 3, 2026, Rockstar sold 31,446,995 copies of the legacy version on PC, making 42 % of all copies sold.
The PC Enhanced version sold 2,785,296 copies, making 4 % of the pie, and the PS5 version sold 13,149,129 copies, making 18 % of all copies sold.
This only covers 74 million copies of the total 225 million copies sold, so the breakdown may be different in total.
As for the earlier data, it implies that Rockstar makes much more money on GTA Online microtransactions on PS5 than PC, but they still sold more copies on PC.
