Is the amount paid as a rental advance for an apartment, which will be deducted from the monthly rental value, considered a debt owed by the landlord in the event of his death?

A lease contract is binding on both parties and is not terminated by the death of either of them. The lessor owns the rent, and the lessee owns the usufruct of the leased property for the agreed-upon period. The death of either party does not affect the contract. Thus, the lessor owns the advance rent, and it is not considered a debt upon him.