All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
This statement has no effect on this brother's marriage; the marriage is still intact and the husband's statement has no legal consequences. Rather, it falls under the heading of idle talk.
It should be noted that Muslim men should not make it a habit to pronounce words of divorce, as this imperils the marriage and makes it vulnerable, while marriage is described in the Quran as a solemn covenant; Allaah, The Exalted, says (what means): {And how could you take it while you have gone in unto each other and they have taken from you a solemn covenant?} [Quran 4:21]
It should also be noted that the Muslim is enjoined to refrain from discussing and arguing about matters of which he has no knowledge, especially pertaining to religious issues. Allaah, The Exalted, says (what means): {And do not pursue that of which you have no knowledge. Indeed, the hearing, the sight and the heart - about all those (one) will be questioned.} [Quran 17:36] The arguing parties should refer to scholars so as to resolve any problematic issues; Allaah, The Exalted, says (what means): {...So, ask the people of the message if you do not know.} [Quran 16:43]
Allaah knows best.