Eidos Montreal has officially revealed the minimum and recommended specs needed for their upcoming Thief reboot for PC on their official community blog. The post mentions work with Dutch development studio Nixxes to make the PC version the best it can be. Nixxes has worked on the PC versions for Deus Ex: Human Revolution and Tomb Raider.
The specs are as detailed below.
OS: Windows Vista with Platform update
CPU: High-performance dual core CPU or quad core CPU
CPU: AMD FX 8000 Series or better / Intel i7 Quad Core CPU
RAM: 4+ Gigs
Graphics Card: AMD Radeon HD / R9 Series or better / Nvidia GTX 660 or better
DirectX: DirectX 11
HDD/SSD: 20 Gigs
Thief is scheduled to come out on February 25th, on Xbox 360, Xbox One, PS3, PS4 and PC. Even though the game is coming out on Next Gen consoles, the game will still be most at home on the PC. So you can expect that plenty of love and care went into the PC version of the game.