I do not see how.

I do not see how. They simply don't have enough troops. Moreover, the Ukrainians let them get into the open - only to hit them by their ATGMs, UAVs, and artillery. Meanwhile, they hit the 2nd echelon by artillery. So, sometimes the Russians come forward, and capture a village or enter one. But many times they turn around and withdraw. That's why the advance is as slow and it appears as if 'nothing is going on'.