I don't think you mean 2K and I don't think you mean 970ti. One isn't a gaming resolution and the other doesn't exist
A 2070 is capable of 144fps gaming even at 1080p with the right CPU, even with the eye candy turned up.
A 2070 is capable of smooth 60-100fps G-Sync/Freesync gaming at 1440p or even 4K if you turn down the details
It's not really clear what you're looking for - silky-smooth 144Hz motion, higher resolution, or both? It would also be useful to know what your CPU is because 144fps gaming is unforgiving on CPUs.
Casual and older games run fine for me on my 4K 60Hz TV with a GTX 970
For the latest AAA titles I use an RTX 2060 and a Freesync HP Omen 32 (2560x1440 VA panel) with a 40-85Hz variable range.
IMO, the sweet spot is to go for the highest details and resolution your hardware can manage whilst staying within the Freesync/G-Sync range of a monitor. I don't want my framerate to dip to 40fps, but if performance is usually enough to hit 85fps, it can easily drop to under 60fps in heavy scenes.