If my target of Discipline gets Gusted, do I get the draw?

Yes — you still draw. Gust resolves first and returns the unit, but Discipline's "Draw 1" is a separate, non-conditional instruction: it executes even when the +2 Might can't be applied because the target left play (Rule 359.3.e.5). Spells always resolve as much as possible — only the instructions tied to the vanished target are ignored.