Without his background in zoos and how certain animals behave, Pi most certainly would have been a small snack of Richard Parker's within the first week of being caught on the lifeboat with him. There are several key bits of knowledge about zoos and tigers that save Pi's life as he tries to survive with the huge tiger on board.
1. He understands the entire "alpha male" concept. He knew that animals cower to the rule of whatever alpha male is in the area. Because of this knowledge, Pi knows that he must establish that HE is the alpha male, NOT Richard Parker. He comes up with the ingenius idea to use the whistle; the whistle terrifies Richard Parker and strikes fear in his heart. So, whenever Richard Parker is fed, Pi blows it. Whenever Richard Parker venture anywhere near Pi's "territory," Pi blows it. This firmly establishes Pi's territory and dominance. Without that, Richard Parker would have most certainly killed him.
2. He understands "tiger langauge." Because he has studied tigers in the zoo, Pi is able interpret and understand all of the different noises and expressions that Richard Parker uses. That enables him to be more safe, to better provide for the animal, and to keep his reign as alpha male. Without that, he would have misinterpreted things and there could have been trouble.
3. Pi's father taught him a valuable lesson about the danger and majesty of predatory animals. He learned that lesson at the zoo as he watched poor innocent animals torn to shreds, in order to learn that tigers and the such are not cute toys to play with, but fierce killers that one should respect. That lesson stuck with him, and because of it, Pi treated Richard Parker as the dangerous animal that he was, and never underestimated his abilities. That saved his life.
These lessons, and many more, helped Pi to survive not only on lifeboat with a fierce 450-pound tiger, but to survive at sea also. He was uniquely prepared for his situation, and it is what helped him to survive for so long. I hope that helped; good luck!