I wouldn't say that they are in control. If they had a lead in excess of 100 runs in the first innings, then I would have agreed with you. But their lead of 69 runs is not something that is very unsurmountable. Even in this test, none of their batsmen (perhaps apart from Ben Stokes) looked capable of confronting the Australian bowlers without any fear.
Australia continues to depend too much on Steve Smith and this may prove to be their undoing. The only other batsman who gave him some sort of support was Marnus Labuschagne (even he was unable to score a half century). All of them failed against the pace of Jofra Archer in a pitch that gave no extra assistance to the fast bowlers.