If for a person to perform hajj some people gift him the expenses for going to and returning from Mecca, and they also gift him the living expenses of his dependants during the time he is on his journey to Mecca, then hajj is obligatory for him even if he has a debt to pay off and even if he does not possess wealth that he can live on when he returns.
However, if the journey for hajj falls on the days when he earns a living and were he to go for hajj he would not be able to repay his debt on time, or he would not be able to pay for his living expenses for the rest of the year, then hajj is not obligatory for him.