Not just lgbtq but all marginalised people. Capitalists are incentivised to create and exploit marginalised people under capitalism. They are not incentivised to solve marginalisation because marginalised people have conditions that make them easier to exploit for lower wages and worse conditions.
Whether it's patriarchy which has always held 50% of the population as property of men for free labour and exploitation, or more recently the gender wage gap. Or whether it's racism, where the marginalised suffer worse conditions, maltreatment, poor wages and a tougher time. Or whether it's lgbtq people where their marginalisation has a 22% wage/earnings gap with hetero/cis people. (don't get me started on sex work or being trans and renting or applying for jobs)
Capitalists gain from exploitation of marginalised groups. You will not liberate any marginalised group fully under a system incentivised to exploit others as marginalised people are ripe for exploitation. If you do liberate one group they are incentivised to create another or shift the burden to an existing one.
The liberation of marginalised people can only come with liberation from a system incentivised to create marginalised people. Various pressures we create achieve concessions for marginalised groups but that's all they will ever be, concessions to prevent us overturning the system entirely.
Gay men in the us earn more than similarly qualified straight men. This suggest it has more to do with gender identity specifically, rather than lgbtq broadly.
Apologies if I'm missing it, but it looks like the claim isn't specific to men in same-sex marriages.
"Individual gay men earn 10% more than straight men with similar education, experience and job profiles,[2][3] and individual gay men who are married have a significantly higher median income than heterosexual married men.[4]"
I read this as unmarried gay men make 10% more than unmarried straight men, and the number is even higher than 10% for those who are married.
a large part of the origin of queerphobia is the rise of capitalism. the shift to the bourgeois-proletariat class separation and especially industrial revolution created the conditions for it. capitalists pushed the family unit, imposed on each worker, consisting of one man, one woman, and several children, to have efficient reproduction for more workers. this pushed specific gender roles for men and women, and then the (often violent) repression of people who fell outside of that standard family unit, such as trans, gender-nonconforming, or homosexual people. this is why bourgeois oppression is interlinked with queerphobia and cishetero oppression and the necessary route for queer liberation is through the destruction of the force that originally brought much of it.