Navi 1 IPC is the same if not a few % higher than Turing, a few pages back a 2070 at 1.5Ghz which has the same 256Bit GDDR6 @ 1750Mhz and the same 2304 Shaders was about 96% the performance of a 5700.
The 5700XT reference runs at about 1850Mhz, the 2070 about 2000Mhz, AIB 5700XT mine about 1950Mhz.... some as high as 2050Mhz, its a 40 CU (2560 Shader) part with 256Bit GDDR6.
The 505mm^2 Navi 2 is thought to be an 80 CU part with 512Bit GDDR6 with a reference core speed of about 2050Mhz with AIB ones as high as 2200Mhz, its 2X the 5700XT +5% core speed and between +5 - 10% higher IPC.
According to the TPU slide above a 2080TI is 142% of a reference 5700XT, doubling the CU and memory bandwidth does not scale 1:1, conservatively we can safely say 0.75:1, so all things being equal big Navi would be 175% of the 5700XT, add +5% IPC and + 5% clocks making it 185% of the 5700XT, about 143% of the 2080TI.
That doesn't seem like a huge leap... but i would like to see Nvidia go 180% or more of the 2080TI to make it a meaningful difference from Big Navi, the 2080TI is 800mm^2 on 12nm, 12nm is 0.7 the density of 7nm, you gain 40% die area going to 7nm, a 2080TI would still be 570mm^2 on 7nm, all things being equal to gain that 80% to put them 30% ahead of Big Navi Nvidia would have to go 1150mm^2 on 7nm.
Good luck with that.