The first obvious rule is 'Anything goes in a song lyric'. Song writers don't always worry about grammar - some of them probably don't even know very much. The important thing for them is writing something that sounds good, rather than being grammatically correct. But - in this case, it's actually OK. I think it is called reported speech. If on Monday, I said 'Czarek, you are going to die on Wednesday', on Tuesday you could say 'Gary told me I am going to die tomorrow'. I told you in the past, something that would happen in the future.

We would usually say "Somebody once told me the world was gonna roll me" If you say "is", the rolling is still in the future at the time you speak: EX: 2 days ago, somebody told me "the world is gonna roll you in 5 days". So, 3 days from now, the world is gonna roll me. Somebody once told me the world is gonna roll me.