Can GTX 660 do 144hz?

It can probably run it but you might have to reduce some game settings to achieve the necessary frame rates to avoid screen tearing.

Can the GTX 1080 Ti handle 4K?

The GeForce GTX 1080 Ti was perhaps the first graphics card that could actually handle 4K gaming without accepting chronically slow frame-rates or greatly diminished graphical settings. All things considered, it sits only behind the RTX 2080 and RTX 2080 Ti on our ranking of the fastest graphics cards on the market.