Mark Bloom's inch-perfect delivery for Defoe looked likely to result in a goal before the former Tottenham Hotspur forward fired wide from just inside the box.
Vancouver were restricted to long-range efforts for most of the first half, and they were fortunate to go into the break level after Luke Moore had seen a powerful header pushed away by Ousted.
The visitors returned with renewed confidence in the second half, and the deadlock was broken in the 50th minute when Vancouver forward Darren Mattocks collected a clever pass from Russell Teibert before firing past a helpless Joe Bendik.
Toronto found the equaliser their superiority deserved just 14 minutes after falling behind when Nigel Reo-Coker brought down Jackson inside the box, allowing Defoe to confidently drill the ball home from 12 yards.
Jackson was inches away from making another vital contribution moments later, but his strike from a tight angle was tipped away by Ousted.
The home side looked most likely to find a winner in the closing stages, but a stubborn defensive display late on allowed Vancouver to secure a draw.