People can watch the clip starting at the 36:38 mark of this to hear for themselves if they want, but I think that it is very reasonable to think that Microsoft is in a position to go all in on CPU customization on Scarlett using the Ryzen Zen 2 cores.
I just finished listening to Phil at Giant Bomb. I remember him emphasizing the balance of CPU and GPU while talking to Jeff at E3 last year, and again CPU is something he mentioned this year. It definitely seems like they have a strong focus on CPU performance and capability.
It does seem like if it was a 12 core part they would've mentioned 6x or just said we have 12 cores. So it's mostly likely they still have 8, but with the way Phil has talked about the balance of CPU and GPU, to me, it sounded like part of it was the physical contribution of the CPU to the overall SOC. Perhaps this focus includes things like hardware for ML or AI, things to reduce the load on the CPU, or can help the CPU to run more efficiently. Back in the 360/PS3 generation the split between die sizes of CPU and GPU was much closer to 50/50, whereas this generation it skewed towards GPU (especially the Pro and X).