It's absolutely not the same performance. 1080 Ti and Titan Xp and 980 Ti and Titan X might have been that way because of die limitations, but that's not the case here. Titan V does better than 20x the DP FLOPs than a 2080 Ti. In a gaming workload they might be similar, but the Titan line was never really created for the gaming crowd. Maxwell was a bit of an anomaly since they never produced a real compute chip, and they chose not to release a GP100 Titan Pascal.
Now, given the performance numbers of the RTX Quadros we know TU102 is capable of 1/2 DP performance and so we could see a future Titan T card with excellent gaming performance and comparable compute capabilities, but who knows what kind of price that that will fetch. I wouldn't be surprised if we see it, but I can't imagine any but the money no object crowd choosing to buy one as a gaming card.
All the original Titans (Kepler, Maxwell, Pascal) were/are
absolutely gaming cards, go to the NVidia site right now and read what NVidia says about Titans. It's all about gaming.
https://www.geforce.com/hardware/desktop-gpus/geforce-gtx-titan-black (Kepler)
https://www.geforce.com/hardware/desktop-gpus/geforce-gtx-titan-x (Maxwell)
https://www.nvidia.com/en-us/geforce/products/10series/titan-x-pascal/ (Pascal)
Titan V OTOH, was big departure it is no longer considered a gaming product, and that card doesn't make sense for a comparison to gaming cards, which was my point. Again go see what NVidia says, all about compute, deep learning.
https://www.nvidia.com/en-us/titan/titan-v/
But I am not the one bringing up this odd duck in the comparison.
Bad marketing on NVidias part to shift the meaning of Titan. But earlier Titan and Titan V are not the same variety of card despite sharing a name.
Which also leads us to why 2080Ti is here early in the Titan X time frame, but not called Titan. It's what would have previously been Titan T, before NVidia changed the naming scheme. It's the Titan X, early adopter high performance card for this release.
If NVidia hadn't messed up their marketing. Titan V, should have stayed a Quadro (or picked a new name), and 2080Ti would have been Titan T, and people wouldn't have gotten so confused and made so many wrong headed comparisons.