how did Rudy and Hans Hubermann help Liesel to become a perpetual survior

I think the best answer would be that Rudy and Hans help Liesel to survive by teaching her to express herself through storytelling, writing, and reading. It provides her a means of escape from the horrors she has to face, and hence keeps her focused on survival. Her language also serves as protest. And of course, because of what they taught her, she becomes a perpetual survivor by creating work that can survive through her generation.