Gilson Manuel Silva Alves also known as Ja (born 18 March 1987 in Fogo) is a Cape Verdean football forward, as of 2013 who plays for Olympique du Kef in the Tunisian Ligue Professionnelle 2.
His first youth club was Batuque, he participated in two other clubs abroad, Rapid Bucharest and Nadi al-Jazira in the Emirates, likely the first Cape Verdean player to participate in the youth player. Gilson Silva appeared in the senior level and his first two clubs were of his nation, Batuque FC in the early part of the 2004-05 season and later Botafogo FC from Fogo. Gelson later played professional clubs in Tunisia including Étoile Sahel (played as of January 2014), US Monastir, Olympique de Kef and Sbiba. In between Étoile, outside Tunisia, he played with EA Guingamp, later he played with Ceuta in the Spanish Leagues.
Whilst at Guingamp, then in Ligue 2, Ja played in the 2009 Coupe de France Final in which they beat Rennes.
Ja has played for the senior Cape Verde national football team in a qualifying match for the 2010 FIFA World Cup.
He married Sandra in 2008 and raised their first child, a daughter in 2009.