You can seek guardianship of the minor, and because the minor has lived with you already, it will likely help your chances in having it granted. If you are not a relative of the minor, the process is a little more involved, but it can be done.
If you do not have the consent of the parents, you will have to have a contested hearing on the issue, and a guardian ad litem will be appointed to make a recommendation and perform a home study. The botXXXXX XXXXXne is that the court will determine whether a guardianship is in the child's best interests. Since you have been caring for the child, that will definitely weight in your favor. If successful, you may be able to get child support from the parents as well.
This is not something that can be easily done without a lawyer however, unless the parents agree to it (and even then, I wouldn't recommend it, but can be done then).
To answer your question- maybe, probably. The court looks at the individual case and circumstances and decides what outcome serves the best interests of the child. If you being guardian is in the best interests of the minor, a guardianship will be granted.
You can start here: http://texasguardianship.org/minor-children/