This is a statement that has been made about lawmakers in Texas. That state, unlike most states in the US, does not have a state income tax. The quote is saying that lawmakers in Texas are extremely unlikely to ever vote to impose an income tax on the citizens of the state.
This quote is a bit of hyperbole. Obviously, handling rattlesnakes would be rather dangerous. It would be the sort of thing that you would probably never want to do. So, to say that someone would rather handle rattlesnakes than vote for an income tax is a way of using exaggeration to say that they would really, really not want to vote for an income tax.