Well as a structural material gold is not good due to most metals being better in every way but for example gold has a tensile strenght of 120MPa while for wood 120MPa seems to be the upper limit after a bit of googling(varies wildly by species, density, moisture and perhaps most importantly grain orientation) so in the context of a same size/thickness etc violin i would wager that the gold one would be quite bit harder to break than the wooden one