Hi.
Does your CPU have integrated iGPU ? or the gtx is for dom0 ?
It is a Laptop or Desktop ? The TV is the primary or a secondary screen ?
It is a scale issue ? (some related links).
https://forum.qubes-os.org/t/global-scaling-for-tiling-window-manager/15357/3
https://forum.qubes-os.org/t/4k-font-size-dom0-vs-vm/3767/10
Assuming you do not have flickering issue with the default resolution (and no other issue),
you do not need to install Nvidia driver.
Does the scaling solution works ?
If dom0 use the nvidia gtx and not an integrated iGpu, nvidia driver may be needed.
But for a gtx 1070, the nouveau driver should work well enought. (to confirm on 4k display).