Strictly speaking, as per law you are not eligible for gratuity. However, there are ways to prove that the business and the actual employer has not changed. This is referred to as piercing the corporate veil. That, you need to show that the actual is the same in both cases, number of people, location, clients and nature of business has remained same.
If you have this information and you can file a claim with your employer for graduates. If he denies the same you can go to the commissioner and file an official complaint. If you can who's your point to head to the satisfaction required under law, you will probably get the gratuity
You cannot do this you leave your job obviously. The other question is do you really have the time and money to pursue this? Remember, it is not compulsory for for the commissioner to give judgement in your favour. If the amount is not very large, just skip it and proceed