No GH has no direct effect on the hematocrit through my experience and what I have been told by an endo.
But it (High hematocrit RBC mass polycythemia aka thickened blood) does come from androgen anabolic use...and can be affected by dehydration.
Most bb'ers are dehydrated and don't drink enough to replenish it through loss in sweating and high protein diets etc.