As per the Payment of Gratuity Act, 1972, employees become eligible for gratuity when they have completed five years of service. An employee who has worked for 240 days in a year is considered to have completed a full year. Therefore, since the employee has completed four years and 240 days, they will be eligible for gratuity, but only after completing five years, whether they work for the remaining period beyond 240 days or not.
For easy reference, I am sharing a link with detailed information on the same. There is a well-known case where an employee won a legal battle in the court of our respected Indian court. This case has now become the benchmark for the payment of gratuity across companies. Unfortunately, I do not recollect the specific case.
[Gratuity Act, Amendment, Acts, Eligibility, Abstract, benefits](http://www.helplinelaw.com/employment-criminal-and-labour/ECGI/gratuity-act-amendment-acts-eligibility-abstract-benefits.html)
I hope this information is helpful to you. This information is shared to the best of my knowledge. I recommend verifying with the relevant authorities before taking any action.
Have a pleasant day.