Polytheism is belief in more than one God. Whether or not JWs believe Thomas was referring to Jesus, they believe John 1:1 calls Jesus a God and that Isaiah 9:6 depicts Jesus as having the title "Mighty God." They also believe that Psalms refers to the angels as gods.
JWs are polytheistic and try to make themselves appear monotheistic. Their doctrine is inconsistent with monotheism and can only be explained as polytheism. They try to combine the beliefs of the ancient Israelites with the beliefs of First Century Jews and Christians as though these were identical. The sets of belief aren't identical; they don't combine very well at all. Combining them leads inexorably to polytheism.
ANL