If a husband says to his wife three times (in joke/ ignorance) “ I give you Talaaq” ,will the Talaaq occur.

One of my friends who has very little knowledge of matters on Talaaq said to his wife ? I give you Talaaq? he said this three times in joke. His wife told him that the Talaaq had occurred , he said it does not occur until given in writing. After this incident they are still living together for last three years. Some people say that Talaaq has occurred some say it has not occurred. Please clarify following things; 1. Has the Talaaq occurred. 2. If the Talaaq has occurred, have they been committing the sin of Zana for last three years 3. If their staying together is unlawful and they have been committing a sin, what should they do now. 4. Is the ?Halala allowed with intention to marry again