That all depends upon how many children actually live to reach maturity and have that number of children, though.
Immortal elves who have any number of children two or greater will be capable of overwhelming the entire world with children.
It's the death rate that balances this all out - you have to hit that "terminal velocity" (heh) where the force of growth rate is balanced out by the force of death, in this case, that would be death to violence and starvation (possibly disease, when that gets implemented).
Having "Completely Gay" elves would functionally just cut the average number of children per couple, but if elves can still have unlimited children from a single couple, that would be meaningless without a death rate.
I also wonder if we should be arguing for strictly monogamous relationships while we are arguing for homosexuality to be included in the game - extramarital affairs, and even polygamy were often caught up in the history of homosexuality.
The Romans, for example, were perfectly fine with bisexuality, but they thought being "absolutely homosexual" was strange behavior, and would socially coerce men of high social standing to take (official) wives to form a social face, even while letting those men go have fun with who (or what) ever they so desired.
Some of the emperors even passed laws that essentially required high-born men and women to produce high-born offspring, through tax and social perk policies, just to keep the population levels of the higher classes up, since they generally had little interest in their actual spouses, and were so busy having their way with slaves (whose children would also be slaves) to actually keep the first-class Roman population going.