Can I pray behind the imam who told us to take supporters as Auliya although they are dead? Islam tells us to pray in mosque now can I perform Salat for this reason?

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Prayer is unlawful behind any person who seeks refuge with dead people as seeking refuge is a form of worship which should be done only to Allah. So, anybody who seeks refuge with other than Allah, he commits a nullifier of the religion and so he could be judged (by scholars) to be a disbeliever, especially if his mistake is shown to him and he does not agree to cease this bad act.
As for the person who calls for such an evil deed, his sin is much greater as he is a person who calls for polytheism. So, you should advise this person and make the truth clear to him and warn him against evil deeds and the consequences of polytheism. If he accepts your advice that is good, otherwise try to remove him peacefully from being your Imam. If that is impossible or if it can cause any problems, then look for another mosque where the Imam is good and pious. As long as this Imam is there you have an excuse to not to attend congregational prayer.
Allah knows best.