Can I get survival benefits if my husband promised them to his 1st wife?

Not if he followed through with the paperwork giving them to his first wife. If she has court orders properly processed, she gets the benefits. If she only has a verbal promise that was never reduced to a court order and submitted to his retirement plan, she cannot claim those benefits.

It depends on what they are?

Whether you are entitled to any surviving spouse benefits depends on the rules, policies and procedures of the particular Retirement Plan involved, and the specific language used in the Judgment of Divorce and the Qualified Domestic Relations Order ("QDRO") between your husband and his first wife. A good first step is for your husband to contact his Plan Administrator to assess the Plan's rules as to "dividing" or "allocating" surviving spouse benefits.