In Texas when you are on a Medical Leave can your employer fire you or do they have to wait until you return to work from your leave?

Assuming you are on a leave of absence under the Family Medical Leave Act, the employer can terminate your employment if they would have done so were you not on leave. For example, if you are a Tech and the employer has decided to eliminate all positions in the Tech classification, they can do so even though you are on FMLA leave. This applies to all federal and state leave laws. However an employer cannot terminate you in retaliation for you taking leave.

Agree, what was the reason for the termination.