There's a difference between PSG scoring 4-0 and Juve with 3-0. Super elite teams like Juve, Manchester United and Bayern will never capitulate in the second leg, because they have elite players and elite mentality. This is game over for Barcelona.
Correct, Juventus defense is far more better than PSG and that's why I too feel Barca is out of the tournament . They should have managed to score atleast 1 goal so that 2 goals in the 2nd leg would have given them the win ( Assuming the clean sheet ) .