Would my nephew have lived had the two tumors not been surgically removed, or had the surgery been performed elsewhere?

The whispers that revolve in the soul are from Satan, who wishes to grieve the believers. The Prophet, peace and blessings be upon him, forbade saying "if only" because it opens the door to the work of Satan. Qadi Iyad said that it indicates an objection to divine decree and leads to abandoning contentment. Al-Nawawi said that it casts opposition to divine decree into the heart. Ibn Uthaymeen said that it opens the door to whispers, sorrows, and regret. What has happened has been decreed by Allah, and no soul will die until it completes its term and its sustenance. Allah refuted those who said, "If we had any say in the matter, we would not have been killed here," by stating that death is written and predetermined.