Noble count is not the determining factor in my opinion anyway. I think gold is. Pian en Luries has very close to the amount of gold income that they do (Auvrendil?, spelling probably wrong) but could never hope to field even 15-20k cs.
It is a factor though. Smaller units are cheaper, and have a higher CS per man/per gold spent as well.
I'm not 100% on how much of a factor it would be, but 2000 identical men spread into 40 units should be cheaper and provide a higher CS then if we spread them into 20 units.
When we talk about gold, the thing is we are so far talking about a rather short term boost to their military strength. Gold supplies can be built up for this, and if there is no gold drain on the realm (tournaments, people sending off gold to the family, food imports) you could build up the gold needed for a big CS boost. Nothing much has happened in the war for a while now, giving them time to build up gold reserves.