my nephew who was born in August 2018 has been on medicaid, Can i claim him as my dependent. For medicaid, would my income be considered for his eligibility? my sister had zero income for 2018 and my brother-in law lives in Canada so i provided most of the support.
We do not know enough about this to say if you can claim your nephew. Why is one of his parents not claiming him? Why do you think you can claim him?
My sister doesn't have any income and my brother-in law lives in Canada. So I provided most of the support when he was born.
my concern is since my sister applied for medicaid based on her income which was $0 but now if I claim him dependent would it revoke his medicaid?
She would have to discuss that with the state medicaid office to get an answer.
You can claim a "close relative" (child, grandchild, niece or nephew, and a couple others) as a qualifying child dependent if they lived in your home more than half the year (or more than half the number of days since they were born). If their parent could also claim the child as a dependent (such as, you all lived together for all or part of the year) then the parent gets first choice, and if the parent agrees to let you claim the child, your income must be higher than the parent's. The child must also have their social security number before you file your return.
In Turbotax, select "the child lived with me all year" for a child that was born in the middle of the year and lived with you since.
We can't tell you if that will affect the child's eligibility for government benefits, that is a question for Medicaid or for an attorney or financial planner.