The first book that comes to mind that I believe has strong parallels to Life of Pi is Gary Paulsen's book Hatchet. Both books have a young, male protagonist that is in a battle for his life in wilderness territory. Brian's plane crashes, and Pi's ship sinks. Both characters are expected to use the extremely limited tools on hand in order to find food, water, and shelter. Both characters are incredibly hampered by the elements, and both characters must draw on deep amounts of inner strength and persevere through a ridiculously tough situation.
For a short story, I like Stephen Crane's "The Open Boat." It's about men struggling for survival in a small lifeboat of sorts. They fight and fight against the elements that seem indifferent to their efforts to survive. Crane also wrote a poem called "A Man Said to the Universe" that also focuses on nature's uncaring attitude toward the plight of human survival.
As for a song, I would go with "Never Give Up" by the reggae band Common Sense. Pi simply...
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