Some say that it is "okay" some say that it is not, but these are just opinions. What does the Orthodox Church thing about that, and how do they deal with it?
According to this article from the Antiochian Orthodox Christian Archdiocese of North America, marriage should be reserved for a man with a woman, and struggle with homosexual desires can have benefit to a person's spiritual growth.
How is the Christian to understand the appeal for homosexual marriage? Persons with a homosexual orientation are invited to use their struggle as a means of sanctification. In scripture homosexual behavior is not blessed by God and specifically prohibited: "You shall not lie with a male as with a woman; it is an abomination" (Leviticus 18: 22); and from St. Paul: "... because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed for ever! Amen. For this reason God gave them up to dishonorable passions. Their women exchanged natural relations for unnatural, and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men ... " (Romans 1:25-27). This is not the same thing as saying that a person who struggles with same-sex desire has lower value in the eyes of God. The focus is on the behavior, not the person.
this post is an example of gay marriage ceremony with Orthodox Church traditions, but it makes it clear that it was not performed in a non-Orthodox church building, and the church's website confirms that the officiating pastor was not Orthodox.