Assuming it's God Cloth Seiya and this is current Superman, Seiya stomps
Otherwise, Seiya can range from Gold Saint level to well below that, due to his cosmo fluctuating wildly for plot-related reasons
Currently in ND, Seiya is a cripple in a wheelchair while in the (non-canon) Omega anime continuity, he's a high tier Gold Saint wearing the Sagittarius Cloth