Wesley Sneijder set the ball rolling in the 12th minute on Sunday when he ghosted into the penalty area to tap home from close range following good work by Felipe Melo.
The Dutchman doubled his tally eight minutes later firing home a left-footed thunderbolt from 20 yards, before Emmanuel Eboue rounded goalkeeper Sebastien Frey to make it 3-0.
And Sneijder completed his hat-trick two minutes before the break, capitalising on a defensive mix-up to send the ball into the roof of the net.
Didier Drogba's deft flick put Roberto Mancini's side five up in the 66th minute, before Selcuk Inan completed the rout with a curling effort two minutes from time to make it 6-0.
Sunday's victory saw Gala take full advantage of Fenerbahce's 2-1 defeat at Eskisehirspor on Saturday.
Dirk Kuyt pulled the visitors level after Henri Bienvenu had put Eskisehirspor ahead, but Erkan Zengin had the final word, sealing the three points in the 83rd minute.
Besiktas kept pace with the top two as they leapfrogged Sivasspor, who lost 3-0 at Konyaspor, with a 3-2 victory over Kayseri Erciyespor.
Kayserispor's goalless draw at home to Kasimpasa saw them climb off the foot of the table.
Elsewhere, Karabukspor picked up a 3-1 win against strugglers Elazigspor, Arkhisar Beldiyespor triumphed over Genclerbirligi by the same scoreline, Gaziantepspor won 1-0 at Antalyaspor, and 10-man Trabzonspor were held to a goalless draw at Rizespor.
