In order for your brother to apply for Medicaid, his share of the duplex needs to be titled in his name only, and your share of the duplex needs to be titled in your name only. Your income should not disqualify him because you live separately (albeit in a duplex) from him. Furthermore, make sure you do not have joint accounts.
The comment provided above is intended as general information and IS NOT LEGAL ADVICE. You should consult an attorney for advice regarding your individual situation. If your question concerns Estate Planning, Trusts, Elder Law, Probate, Trust Adminstration, or Guardianship, and is governed by the laws of the State of Texas, then you might wish to contact our firm, which is The Mendel Law Firm, L.P., 1155 Dairy Ashford, Suite 104, Houston, TX 77079, O: 281-759-3213, F: 281-759-3214, email@example.com