Winston is currently involved in two investigations, one for a sexual assault accusation from 2012 and another looking into whether the quarterback sold autographs. He faces a disciplinary hearing at Florida State for the first.
"Jameis Winston needs to make some changes in his life," Jackson said. "Because it's affecting him now and it's definitely going to affect him down the road."
On Sunday, FOX Sports' Jay Glazer reported that Winston is falling on NFL draft boards. Winston was recently suspended for a game after reportedly yelling an obscene phrase in the campus student union.
Winston's lawyer said Tuesday that the upcoming student conduct hearing will have "no impact" on Winston playing the rest of this season, and Seminoles coach Jimbo Fisher said he is "very confident" nothing will come out of the autograph investigation.
No. 2 Florida State (6-0) faces No. 5 Notre Dame (6-0) on Saturday.