Answer
Yes, you can dissolve it.
Work Step by Step
$AuCl+2\ CN^-\leftrightarrow Au(CN)_2^-+Cl^-$
$K=Ksp\dot{}Kf=4.0\dot{}10^{25}$
With such a large constant, the limiting factor to the solubility is the availability of the cyanide ion, which in this case, with 6.00 M vs 15.0 mg/100.0 mL, wouldn't be an issue.
Yes, you can dissolve it.
