Christian Pese, 18, suffered a stroke earlier this month while playing for the South Island in the NZRL National Under 20s tournament.
The Otago University law student remains on life support at Christchurch Hospital - where most of his immediate family have travelled to from Auckland.
Family friend Cherie Whaanga set up a Givealittle page, which has already raised more than $16,000 for the family.
The money is set to go towards travel expenses and costs for the family to remain by his side and help fly Pese's eldest brother, Caleb, over from Australia.
"Christian comes from a strong, loving and supportive family but he is fighting for his life right now down in Christchurch," the Givealittle page description reads.
"His family is based in Auckland but have all travelled or are travelling to be by his side.
"Christian had only just set himself up down in Otago when this happened.
"His family is devastated, their eldest son Caleb is desperate to get home from Sydney and they all need to be able to be together again. It is now time to hope and pray for a miracle!
"Please help us lessen at least one burden for this family over this time.
"Christian we love you and you are a fighter! Arohanui to Korey, Joanne and all of your beautiful whānau."
The NZRL were unable to provide an update on Pese's "ongoing condition".
