I am 25years old, but work a full time job and am not a dependent. If my step dad payed my tuition but he is not claiming me then can I claim it instead?

Yes, if you are not a dependent of anyone you can claim the tuition that your stepfather paid. It's treated as if he gave you the money and you paid the tuition.

you will also get to claim your personal exemption. Whoever gets the exemption, claims the 1098T

Yes, you can claim it.