Revealed over at the official website, both the minimum and recommended system requirements for Mafia 3 include 50GB of storage space and at least Windows 7 64-bit OS. To run the game, you'll need at least an Intel Core i5-2500K or AMD FX-8120 CPU, 6GB of RAM and Nvidia GTX 660 or AMD HD 7870 graphics card with 2GB of VRAM.
These will probably let you run the game at 1080p and hopefully include at least a decent level of detail.
In order to get a bit more from the game and possibly include all the eye candy at a decent resolution like 1080p or 1440p, you'll need a bit more hardware power, including an Intel Core i7-3770 or AMD FX-8350 CPU, 8GB of RAM and Nvidia GTX 780, GTX 1060 or AMD Radeon R9 290X graphics card with 4GB of VRAM.
In case you missed it earlier, Mafia 3 is set in New Bordeaux and follows the story of a Vietnam veteran, Lincoln Clay, who gets in the middle of a fight with the Italian Mafia. The game is set in 1968 and will include some neat details from the 60s, including cars, weapons and more.
The Mafia 3 will launch on PC, Xbox One and Playstation 4 on October 7th.