The evidence used in the theory is that Pascal cards runs with the same performance Ray-tracing.
TITAN V
30-12-2018, 19:06:48 bfv.exe benchmark completed, 38930 frames rendered in 548.360 s
Average framerate : 70.9 FPS
Minimum framerate : 51.7 FPS
Maximum framerate : 97.4 FPS
RTX 2080 TI
30-12-2018, 19:21:57 bfv.exe benchmark completed, 22472 frames rendered in 317.438 s
Average framerate : 70.7 FPS
Minimum framerate : 55.3 FPS
Maximum framerate : 101.1 FPS
It is a bit of a remarkable story really, but users have enabled RTX mode on a Nvidia Titan V, which works quite well and performs as fast as the RTX 2080 Ti. Titan V, however, is Volta, and Volta do...
www.guru3d.com
I at time disagreed saying the most probable is that game didn't use RT Cores but it is a theory.
Like people are making here about ray-tracing on PS4 being executed in a multi-purpose hardware unit.