Are humans an eusocial species?
The question of homosexuality and its role in nepotism is interesting.

According to this wiki article, less than 10% of the population is homosexual. If you consider that homosexuality makes human eusocial because homosexual do not reproduce but help their brothers and sisters to reproduce, then you would have to consider any species where a few percentage of the population produce some kind of altruism to be eusocial. Given that all phenotypic traits theoretically have social impacts, then I would bet that you might call eusocial a lot of species.

It seems wiser to me to limit the definition of eusocial when an important part (maybe 98% minimum) of the population do not reproduce but help others to reproduce. One might also want to consider some other restrictions for a the use of the word "eusocial"

Therefore, using the argument of "reproductive division" I would rather not include Homo sapiens in the list of eusocial species. But it is nothing more than a question of definition. You're free to define your words the way you want and call human eusocial but make sure your interlocutor knows your definitions.

Now, let's say we place the limit to the definition of eusociality at 1%. When more than 1% of the population does not reproduce but help their kin to reproduce, then the species is eusocial. Then, humans would seem to fit in this definition at first sight. But do homosexual in our modern society really help their kin to reproduce? In other words, do siblings of homosexual reproduce more (or have offspring that have a high fitness)? This study investigated the question (as pointed out by @oreotrephes in the comments) and they indeed found some pattern but the difference in reproduction between relatives of homosexual and non-relative of homosexual is is quite weak. But if homosexual don't reproduce and don't help their kin reproducing then, humans is definitely not a eusocial species.

Finally I want to add that individuals from lots of different species have been found to perform homosexual behaviour (see this wiki article). If you want to consider human as eusocial because some homosexuality, then you will have to consider sheeps, labradors and pigeons to be eusocial as well!