Sulphur dioxide gas reacts with hydrogen sulphide to give rise to sulphur and water, not oxygen.
A little drop of water activates the reaction between the two gases.
Despite it is a redox, the equation can be easily balanced by trials and errors.
Having two oxygen atoms in the reactants, we need four hydrogen atoms, that is two
Taking in account that sulphur is octaatomic and the least common multiple between 3 and 8 is 24, we must multiply every coefficient by eight to have the very complete equation: