Yes, I think that the gay culture is getting more and more accepted by the culture here in the US. I think that in a few years it will be legal for gays to get married and have it recognized by every state. They already got rid of do not ask do not tell in the military.
Yes, gay culture is becoming part of the mainstream global culture. There are more and more shows on TV with gay couples as the main characters, gay marrige legislation is being passed all around the country and the world. Like it or not, gay culture is becoming more and more mainstream.
Something strange has happened in recent years. There was a time when gays, marginalized from society, invented their own free love culture that rejected monogamy because they were not allowed to exist in mainstream society. Now, they are open and out and demanding the rights for marriage, while a "hook-up" culture has spread across straight youths, especially in the urban areas where homosexuals tended to propagate in years previous.
No, gay culture is not becoming a part of the mainstream global culture, because gay culture is still the minority. The vast majority of people are not gay and do not engage in a homosexual lifestyle. What is there has become more tolerated, but that is very different from it being typical.
There are some countries now that approve of gay culture, including the United States and many European countries, but around the world there are many countries in which being gay is still a crime with very severe penalties. It is a topic on which opinion is very divided throughout the world.