Griese, 33, played for Chicago in the last two seasons before rejoining Tampa Bay. He replaced Jeff Garcia as the Bucs' starting quarterback after they lost to the New Orleans Saints 24-20 in their season opener Sept. 7.
Against Atlanta on Sunday, Griese completed 18-of-31 passes for 160 yards and one touchdown with no interceptions in a 24-9 victory.
Tampa Bay rushed for 164 yards and two touchdowns while the defense intercepted Atlanta rookie quarterback Matt Ryan twice.
"[Griese] managed the game," Gruden said. "I think he'll get better and better."
Garcia was the Buccaneers' starting quarterback last season when they won the NFC South title.
He missed almost all the preseason training and practice games with injuries and did not look sharp against New Orleans.