During Pi’s ordeal on the lifeboat, Pi turned to his religions many times. I believe Pi might not have survived if he hadn’t turned to God. Pi used simple symbols from his religions.
For example, Pi saw the color orange, a Hindu color meaning survival, on many things such as the lifeboat and the lifejackets. Another instance is that Pi recalled seeing people from his religions. Such as, Pi states that the orangutan on the island of bananas looked like Virgin Mary floating to the lifeboat. Just as the orangutan was killed looked like Jesus Christ on the Cross.
Pi also used stories from the religions to compare to things that happened on the lifeboat. For instance, Pi states “I felt like the sage Markandeya, who fell out of Vishnu’s mouth while Vishnu was sleeping and so beheld the entire universe, everything that there is”. Another example is when Pi states that “I felt I was living the martyrdom of Saint Sebastian”. Pi constantly continued to pray in the morning, at lunch and before bed. I suppose you can say the belief in God kept Pi alive.