Pascal is expected to be made on a 16nm (16FF+) process by TSMC, the tape-out reportedly occured in June 2015 but this doesn't mean the chip is coming anytime soon of course. The first professional cards based on the GP100 may arrive sometime in Q2 2016, while gamer variants are anticipated sometime around Q3 2016.
If the rumors are correct, Pascal is a DX12.1 (DirectX 12 feature level 12_1) GPU with 17 billion transistors, 4500 to 6000 shader units, HBM2 memory support for up to 32GB (16GB for the GeForce versions), 4096-bit memory bus, NVLink support for the HPC versions, and performance 60-90 percent higher than that of a GM200 (Maxwell).
Via: TPU