Those development kit leaks had this info;
Four ARM Cortex-A57 cores, max 2GHz
NVidia second-generation Maxwell architecture
256 CUDA cores, max 1 GHz, 1024 FLOPS/cycle
4GB RAM (25.6 GB/s, VRAM shared)
32 GB storage (Max transfer 400 MB/s)
USB 2.0 & 3.0
1280 x 720 6.2″ IPS LCD
1080p at 60 fps or 4k at 30 fps max video output
Capcitance method, 10-point multi-touch
However you have to bare in mind that development kits can be much higher performance than the final product. As was the case with the wii u. I think the wii u development kit had 320 stream processors so the 352 gflops figure you often see but retail wii u's only 160 stream processors so the final 176 gflops figure.
It will probably be the same here as others have stated a 500 gflops figure although I don't know where they have got this from.
Anyway development kits normally indicate the absolute maximum spec the reality is almost always less. Original xbox for example having 128MB for the development kit but 64MB for the final costed product.
