We have a customer who has a TX drivers license and an I TIN because it starts with 9. Is he considered a non resident alien or is he a resident alien?

Are you making a determination for tax reporting purposes or for immigration status purposes? If taxes, you can take a look here: http://www.brynmawr.edu/controller/documents/AlienvsNonresidentAlien.htm

Jfredo, asking an individual their citizenship status is your best bet because an ITIN can be issued to either a RA or NRA.

From the IRS website:

Other examples of individuals who need ITINs include:
• A nonresident alien required to file a U.S. tax return
• A U.S. resident alien (based on days present in the United States) filing a U.S. tax return
• A dependent or spouse of a U.S. citizen/resident alien
• A dependent or spouse of a nonresident alien visa holder

Doedoe has provided an interesting, to the point resource.

Having a state drivers license has no implications for residency status; they can be obtained by both citizens and non citizens. A resident alien will have an SSN. Only a non resident alien would have an ITIN.