The father of two suffered injuries to his back, under his arm, upper leg and lower leg.
"He is critical but stable and his prognosis is looking good. We are just happy he is alive," said Kotze’s brother-in-law, Mark Lalse.
He said that the family didn't understand why Kotze was attacked but believed it might have been a case of mistaken identity.
Police spokesperson Lt-Col Thulani Zwane said that a case of attempted murder was being investigated by Sydenham police.