No, and it's not even close. An estimated 20 million Americans identify as LGBT [1], compared to ~3.5M Muslims [2].
I wonder what might make someone underestimate the number of LGBT people in the US. Maybe... a lack of representation in popular media?
[1] https://thehill.com/changing-america/respect/diversity-inclu...
[2] https://en.wikipedia.org/wiki/Islam_in_the_United_States