Chiphell forums leaked a GPU-Z screenshot of NVIDIA GeForce GTX 780 Ti ultra high end graphics card. As speculated previously, GTX 780 Ti has Kepler GK110 GPU with 13 of 15 SMX units available. This makes up 2496 CUDA cores and 208 texture mounting units (TMUs).
GPU is running at 902 MHz base clock with boost clock of 954 MHz. 3 GB of GDDR5 memory connected to GPU via 384-bit bus remains the same at 1502 MHz (6008 MHz effective) clock.
In comparison, GTX 780 has 2304 CUDA cores with 192 TMUs and GPU running at 863 MHz base clock with 902 MHz boost speed, while GTX TITAN boasts 2688 CUDA cores, 224 TMUs and 837/876 MHz GPU clock. It's very possible that due to higher clock and just a slight difference in architectural units, GTX 780 Ti's gaming performance would be comparable to GTX TITAN.
There's also possibility that at some point NVIDIA will release GTX TITAN ULTRA graphics card with fully unlocked GK110 GPU (2880 CUDA cores, 240 TMUs) or its upgraded version called GK180.