If you follow the Payment of Gratuity Act, he may not be entitled to get gratuity. However, since he has already completed four years of service and you are sending him out before the project comes to an end, your act of demanding or even requesting his resignation shall only be treated as an effort to avoid payment of gratuity. That will not be allowed, and the notice period to which an employee is entitled shall be counted as service. If so, he will be entitled to gratuity. I hope you have a notice period clause in your appointment order served to the employee stating that the employee should serve a one-month notice if he wants to leave, and if so, that clause is applicable to you as well.
As the project has not come to an end, and there was no predetermined date of the contract's expiry with the employee, your request to the employee to resign shall also mean that you are terminating or retrenching his service. If so, you are liable to pay him retrenchment compensation at the rate of 15 days' salary for every completed year of service, which amounts to five years. On the other hand, if he serves the full tenure of the contract and is terminated upon completion of the project, you need not pay retrenchment compensation.
Either gratuity or retrenchment compensation is a must. Both amounts are almost equal, but gratuity will be slightly higher since it is calculated based on an average salary for 26 days, whereas retrenchment compensation is based on 30 days. The risk is that if you retrench him now and the employee approaches the Payment of Gratuity Authority, they may rule that gratuity should be paid. If so, your liability would be doubled.
Regards,
Madhu.T.K