The main difference with the Titan X is a lower number of activated SM units and the switch to GDDR5 memory. The site writes the GTX 1080 Ti has 52 SMs with 64 cores per SM, resulting in a total of 3,328 CUDA cores. It has a 384-bit memory bus and the same 12GB memory capacity as the Titan X, but of the GDDR5 instead of the GDDR5X variety. The base clockspeed is said to be 1503MHz, with a Boost clockspeed of 1623MHz. The card has a 250W TDP and delivers raw computing power of up to 10.8 teraflops.
This could be just another fake rumor so take it with a grain of salt. A potential launch date could be CES 2017 as NVIDIA hinted at some big launches at this event.