Depends how deep the lines are. They have breached the first line at some points. However as per ukrainians, after the first line is the second line and so on. Russia knows how to make deep defences and anywhere, where they lose one line, they will adjust and start added more lines to the rear to compensate for the lost line. First line lost, second line is now first line, third line is second and so on and add the new Nth line, since the old Nth is now Nth-1 line.

It will be a slow slug and battering ram fest, unless Russian army morale breaks/ supplies exhaust and they run.