Gums do not really grow back after being cut.
But what the gums do is heal like your skin does and then the gums attach back together and seal the cut naturally after a week or so.
It takes time for the gums to completely heal but they will eventually heal after the gums are cut.
I had my gums cut for dental surgery and after a week the gums started healing and within a month the gums were grown back and were completely healed.
So if your gums are cut then they should grow back or at least heal and it will be like the gums never were cut.
The time it takes for the gums to heal depends on how large of a cut was done to the gums.