Does the air space give R-value in the Wall System?

air is essentially the active insulating material; the fibreglass or plastic stops convection currents forming

No, because R value, by definition, is the resistance of an insulator to thermal conductivity and air is not considered a thermal insulator.

Additionally, any air in the wall space will become subject to movement at some point because no wall is sealed perfectly. When this happens, the air will effectively operate as a heat conductor, reducing effective R values.

Actually, a pure vacuum space would be a perfect insulator because there would be no matter to conduct thermal energy.