How long would a child live if...?

He is under 5 years old; a kidney and liver cancer survivor currently battling AML Leukemia, had an unsuccessful bone marrow transplant.The patient has no kidneys and has been receiving dialysis and waiting for kidney transplant. The patient has a central venous catheter and was undergoing chemotherapy, recently developed a bad infection and is in septic shock with liver failure. If all treatments were stopped aside from pain management, how long would it take for said patient to die?