Is a grad school loan considered "paid by the students own funds" for 1098T tax purposes? I can claim child for one more year (split undergrad / grad year).

Whether your student is a grad student or undergrad has no bearing on whether you can claim him as a dependent or not.  A student is a student, whether high school, college or grad school.  What matters is age and support. The student must be under 24 on 12/31/19 and must not have provided more than half his own support for the year.

Student loans (grad or undergrad) are counted as  "paid by the students own funds" , unless you co-signed the loan.

You can claim the more generous American Opportunity credit , for one more year  (split undergrad / grad year), assuming you have claimed less than 4 times before.  You may only count the undergrad expenses.