Localized, Treble is male.
Mega Man 7: "I'm Bass and he's Treble. We have been trying to stop Dr. Wily while you were gone…"
Not sure about Gospel in Japan, though.
Rockman 7: "おれはフォルテだ，こいつはゴスペル [I'm Forte, this is Gospel] おれ達はワイリーのてから世界を守るために戦っているんだ…" [We are fighting to protect the world from Wily…]
Rockman 7 Transcript / Translation on Hondoori Game Center blog
Forte introduces himself using "ore wa" [I am] which is very macho and informal. "Ore is used by men who are too "cool" for the word boku."
He later uses "ore-tachi wa" [we are] and there's "ore" again. Macho macho macho.
Gospel is introduced "koitsu wa" [this is/this guy is] and… I'm going to defer to some rando on Stack Exchange here:
Roughly speaking, こいつ, そいつ, and あいつ mean "this/that guy", except they're gender neutral. Essentially, they're colloquial, and slightly rude, variants of この人, その人, and あの人, which mean "this/that person"."
So Gospel is only referred to in a gendered way when Forte is speaking about the both of them.
HOW ABOUT THE CD DATABASE, EH?
ゴスペル [Gospel] フォルテをサポートする、オオカミがたロボット。 [A wolf robot who supports Forte.] アダプターに、へんけいしてフォルテと、がったいできる。 [Is able to transform into an adapter and combine with Forte.] 「GRRRRRR!」 ちょうしょ：やせいのかん [Good Point: Wild Nature] たんしょ：かみぐせ [Bad Point: Biter] すき：おんなのこ [Likes: Girls] きらい：ラッシュ、タンゴ [Dislikes: Rush, Tango]
Rockman & Forte CD Database Transcript/Translation
(Side note: Google translate absolutely, hilariously butchers this because inexplicably it cannot understand the word 変形 "henkei" [transformation] when it's written in hiragana へんけい.)
There's no pronouns used here. Gospel is said to like girls, and the older Mega Man games are very, very locked in on traditional gender roles. So the reasonable take here would be "Gospel is a boy wolf robot who likes girls", but the CD profiles are very brief and often extremely vague so when it says he likes girls, does that mean… "gets along better with girls"? (Possibly because he's tired of Forte's constant rude crude dude behavior?) Does that mean "attracted to girls"? I don't think there's any wrong answers here.
TL;DR: Treble is masculine gendered in English game canon. Gospel does not appear to be gendered in Japanese game canon.
If by "super fan" you mean "been in this fandom for longer than some of y'all been on this Earth", gotta say I headcanon Treble as a literal bitch and have for many years now. My vote is definitely keep her as is and I wish the whole fandom would accept "Treble is a girl because I said so". Really, why shouldn't she be?
Bonus fun fact!: 一体と一匹 means "one and one" or "one and the other" (in reference to Forte and Gospel). 一体 [one person]*, 一匹 [one small animal]** also used to count feral people, bad kids, robot dogs (ie: Aibos), tamagotchi, computer viruses, oni.
If I were a translator (which I'm not), I would say "a beast" would be the most accurate translation for 一匹 but English has a whole bunch of different words for this very specific and esteemed group: A critter. A creature-- or, more accurately, creecher. A li'l monster. A beastie. And if they're dog-shaped? A doggo, a puppy, a pupper, a good boy, etc.
In context probably "a boy and his dog".
*(Robots are technically referred to as 筐体 literally housing/casing in the sense of the tower for a desktop PC, the chassis of a car, etc.)
**(Strangers on the internet said if you want to emphasize their [Aibo robot dog] machine aspect, you might use 台; or, if you want to treat them like a person or a member of you family, you might use 人 instead.)
(Response to this thread @befriendthemurderfox)
