Look at your lease, it might have a set fee for breaking it.
Also, since you did not pay anything yet, the landlord will have to sue you in court to get the money. I'd probably start off by negotiating with him. He might cut you a deal if he thinks he can re rent the place quickly rather than go to court.
Make sure that if you pay you get it in writing that he lets you out of the lease.
You have signed it and are therefore obligated. If you simply tell the landlord your financial situation is such that you realize you can't afford it they'll probably let you out with a 30 days fee, or something but they could demand you stay for the lease term.
It is a contract, you signed it. You are not stuck you simply must honor your agreement or pay the price of breaking the lease.
Talk to the person and see what they say. I certainly wouldn't pay them anything. Most won't sue. So just be nice. If they want to they could sue but they are unlikely to do so.
