Yes, it is possible, and we routinely do this when making calibration curves for water content. Gravimetric data is the primary direct measurement of water content available. Almost all other methods are calibrated, that is, dielectric permittivity is what is actually measured and correlations to water content are made.

The only thing you really need to convert your gravimetric data to volumetric data (and vice versa) is the bulk density of the soil. That gives you a g/cm3 (the density of water at STP is very near 1) and you can just cancel the units until you get g water/ g soil.