There seems to be a misconception on how teraflops relate to gaming performance, this is partly due to Microsoft's emphasis on 6TF for their Xbox One X marketing, and now they're emphasising 12TF on the Xbox Series X.
GPU's are far more complicated than that. In the context of supercomputers, then Tflops can be used to ranked the sheer calculation performance.
So a little breakdown of gaming GPU's and their Tflops can be found in this table:
|RTX 2070 Super||9.062|
|RX Vega 64||12.7|
|R9 Fury X||8.6|
|Xbox One X||6|
1, If Measuring performance this way was comparable then, 2080ti would tightly match the Radeon 7
2, Vega 64 would be better than a 2080
3, R9 Fury X would be comparable to a 2070 super
How do these comparisons work out? (Using userbenchmark. due to different games and different DirectX under different platforms working different, using a single overall means of comparison would do.
1, 2080ti is 52% Faster despite having lower Tflops.
2, 2080 is 24% faster (https://www.youtube.com/watch?v=7kP0j_PzS-4&t=282s Even with a 2060, it handily outperforms the vega 64 with it's 'measily' 6.4 Tflops)
3, 2070 super is 67% faster
This is obviously not a surprise to anyone, but shows that there are much more that comes into gaming performance on a GPU, including TDP, Memory size, memory speed, core clock speed, core count etc etc etc.
12TF tells us nothing about the performance capabilities of both the PS5 and Xbox Series X. If anything it's probably gonna be like a RX 5700 XT 'super' edition. As the base 5700 XT is 10 TFLOPs.
PS4 and PC gaming
AMD Ryzen 9 3900x
Zotac Nvidia RTX 2070 Super
32GB DDR4 Corsair Vengence Ram 3200 mhz
1TB Samsung Qvo SSD
Corsair Spec-Delta Case
Asus ROG B450-F Motherboard