According to this leaked statement comes Mi Mix 2 processor Snapdragon 835 SoC paired with 6 GB of RAM, which as a result makes 1929 points in the single core test and 6431 points in multi-core test. It also confirmed the statement that Mi Mix 2 will have Android 7.1.1 OS as Nougat.
Other specifications (according to previous speculations) are Mi Mix 2 will probably be 128 gigabytes / 256 GB internal storage, 19MP rear camera 13MP front and 6.4-inch-edge AMOLED display with resolution 2540x1440px. Batteries should then have a capacity of 4,500 mAh. It seems that we are not so far since the official launch, so we will soon be able to know the complete specs of this phone.