No, it is not revoked automatically. Even though being married gives a spouse substantial rights in regards to his/her spouse, such as to make medical decisions in some cases, or to encumber him/her to certain debts, or to inherit property, a person can also designate non-spouses to have those rights by things like advanced directives, powers of attorneys, and wills, and those documents--and the authority or rights they grant--are NOT revoked by marriage since they can exist alongside marriage. For example, you can be married but still give a trusted friend or sibling a power of attorney to act for you, or will most of your property to someone other than your spouse. Similarly, an advanced directive is not automatically revoked by a subsequent marriage, though the person making it could revoke it if he/she chose.