There are two phrases here:
What's the odds? = What difference does it make?
What are the odds? = What is the likelihood?
odds: The likelihood of the occurrence of one thing rather than the occurrence of another thing, as in a contest: The odds are that she will get the nomination on the first ballot. http://dictionary.reference.com/search?r=67&q=odds
Idiom: What's the odds? colloq
What difference does it make?; What does it matter? http://www.allwords.com/word-take
Collins German dictionary
What are the odds on...? -> wie sind/stehen die Chancen, daß ....?
What's the odds? -> Was macht das schon aus?
From personal experience I also know that "What's the odds?" can mean the same as "What are the odds?" (Wie stehen die Chancen?) but I couldn't find it in a dictionary.