Strictly as phrased, I'd say yes: More lean angle, all other things equal, will bring more speed.
However, we don't just want more speed, we want the most speed we can build. And that means that the angle of the ski to the course and the angle of the skier relative to the ski are both very important. With a ski angle of 90 degrees, you could lean as hard as you want and would just create more load. And if you leaned way over with the ski pointing straight (i.e. 0 degrees), then you'd just fall to the side.
The optimum speed comes from a ski angle somewhere around 45 degrees to the direction of tension and the skier leaning relative to the ski rather than just away from the boat. To most of us mortals, this will feel like leaning way forward, which is scary because it's easy to confuse that feeling with BENDING forward (i.e. at the waist) which is OTF city.