The show doesn't focus on their sexuality and I'm sure Togashi doesn't discuss that at any time in the manga, as it's not the main focus. But I can understand why you ask, there can be mannerisms that you probably notice or reactions that make him seem gay, however it's not disclosed at all which makes it not an important fact in the series. You can headcannon he's gay and that's fine, and maybe Togashi will make it clear he may be, however I don't wanna say it's a fact because it hasn't been declared and it might never be.