You seat is pretty much shot.

You cannot repair it to look good. The best you can do is get a heavy cloth patch of a similar color, cut the patch so that it is larger than the torn area and insert the patch into the hole. Apply flexible fabric glue to the patch where it is under the seat coving, place a sheet of wax paper and then a weight on the patch for several hours.

It will look like an obvious patch, but it probably is better than the open hole