The coupling of Higgs with gauge bosons can receive non-decoupling corrections due to heavy quanta. Deviation from the SM predictions are described by a set of parameters e_V, which can be related to the parameters S,T. The Higgs production by gluon fusion can be used to probe e_g, whereas its decays into WW can probe e_W. The resulting bounds may imply the exclusion of heavy particles, such as additional standard or mirror families, chiral colored sextets and octet quarks. Within the MSSM, we also find that gluon fusion is a sensitive probe for the spectrum of squark masses.