Finer the geometery, smaller are the gate delays. But yes a gate delay may depend upon a number of factors. Such as voltage, output load, input slope, temperature.
As the geometery shrinks, the output load on a gate is likely to shrink, which will help reduce gate delays. The channel lengths are also shorter, so less delay again. But lower voltage could cause more delay.
The net effect is however less propogation delays for finer geometeries.
Kr,
Aviral Mittal