The answer to the original question largely depends on the resolution of your screen, as well as what kinds of games and settings you are targeting.
At higher resolutions like 1440p and above, a 1070 Ti would often be the limiting factor as far as performance goes in recent, graphically demanding titles running at higher settings. And over the coming years, it may become less than ideal for running many new releases even at 1080p without turning the graphics options down a fair amount, as games shift to targeting the new generation of consoles and newer PC hardware. For the time being, it will probably be decent enough though.
Since it sounds like you already have the 1070 Ti, it may be worth sticking with it for now, since the prices and availability of graphics cards have been terrible for a number of months due to a major shortage, and it will likely take a while for them to recover. Anything worth upgrading to is going to be hard to find for anyone not willing to pay over double MSRP.