The lease is a contract with a start date so that is a claim to the place. Reach out to a housing or contract lawyer (there are free services in the state) and explain the situation. The current tenant has a move out date. If they have made it clear that they are not leaving at that date the landlord should be preparing to evict. That’s not your place but you should speak to the landlord to make sure they are going to deal with it. As soon as there was an executed lease, you are under contract. I don’t think you’ll be legally obligated to pay rent to keep the contract valid but an attorney can explain everything.