I personally don't think it matters much at all, except in channels that specifically identify that way. However, I am male, hetero, cis, so its possible I'm just clueless.
I'm not quite grasping the context you're asking the question, but I will say gender matters on Lemmy in the sense that I want full representation from all genders (and non-gender folk). The value of conversation here is derived from the many viewpoints that each of us bring. Without full representation, we'll be missing valuable inside and perspective if a specific gender (or non-gender) is missing.
I'm primarily interested in the opinions of people who are not at least one of male/hetero/cis; it's too easy for the privikeged group to delude themselves about how good they are behaving.
Transfem here, generally unless the topic being discussed is gender specific users genders aren't relevant. Though, Lemmy has a pretty bad track record with gender relations imo, the whole women choosing the bear thing was such a shit show. The men's lib community is good though, I've interacted with a couple posts there that popped up on my feed while scrolling and it actually consists of users who are empathetic and understanding and not anti-women like the reddit one turned into. It's interesting, Lemmy has many many more male users than female, and it goes a bit further, with the ratio of transmascs to transfems being reversed. I just think it's interesting that it's an amab/afab split rather than a gender split. As someone in the thread trans-hatingly put it, "even the women are men here."