Labour's immigration spokesman Rajen Prasad said deporting Mr Kumar was "heartless", because he had a kidney donor in his family and was raising the $130,000 for the transplant.
"His family is meeting all his expenses and he is not seeking any resources from the Government. His only request is not to be sent home on Friday and be given a grace period for him to continue receiving dialysis treatment in New Zealand."
Immigration New Zealand said Mr Kumar had already incurred health costs of around $30,000.
Ms Gardiner said: "It's important that all migrants have an acceptable standard of health to minimise costs and demands on New Zealand's health services."
Mr Prasad said it was a life and death decision, but Immigration New Zealand confirmed that dialysis facilities were available in Fiji.
Mr Kumar's visa was not renewed because a labour market test found there were New Zealanders suitable or trainable for his job as a metal tradesman.