Traditionally published author here. From personal experience, let me tell you: unless your comic is huge (and I mean HUGE, think Solo Leveling or Heartstopper levels), traditional publishers aren't probably going to care about your online presence at all
Edit to clarify: that is to say, if they think your work is worth publishing, they will publish it, follower counts don't matter.
They just don't have the time to check online profiles and whatever: they're barely going to read the materials you've provided them (story summary, your CV, the first few lines/pages of your story if you're lucky) and that's about it. If they like what they see, they might decide to check what other works you have available, but given the tight schedules the great majority of publishers tend to work with... most likely, they'll not. They simply have no time to: they probably already have 20 other manuscripts to check before the end of the day, they're tired and stressed and frankly not paid enough for the job they do
Tbh, tho, having your series already available online for free may even prevent you from getting a contract, because most publishers want 100% original, previously unpublished work and, to them, even self-published works count as "published". It's a bit different with famous authors, because publishers know that there's already a big and established audience for them and, as a result, will be more willing to take risks.
Now, some publishers are less picky than others and may still decide to publish your work even if it's already available online (but they'll probably ask you to take it off any platform it's on so people don't just go get the free online version instead). Some publishers may decide to pick you as an author and will let you have your characters and setting, BUT they may want you to change the plot completely compared to what was online, so that you can retain your old audience but still end up with a work that feels "fresh" (happened to a couple of comics in my country, the original self-published versions had very different plots compared to what was published, but characters were the same). It all depends on the publisher, really.
Best way to figure it out is just... look for publishers who have open submissions, study them for a bit (figure out their target, general style, the kind of stuff they do/don't do... you certainly don't want to send a gore horror story to a children's publisher XD) and see what they ask for. Most will ask for a cover letter, a CV listing your previous publishing experiences (if any), a summary of the work you intend to submit. Some may take the full manuscript/volume (rarely with comics), other will only want a sample, others will just take the summary and contact you later to read the whole thing if they're interested.
A good way to build a portfolio is to look for short story competitions and such. Even if you don't win but manage to get nominated for an award, you can still put it in your CV
Just be very careful and look out for scams (e.g. publishers making the competition winner pay for their work to get published and/or copyright issues that would strip you of any right over your IP).
tl;dr: publishers don't generally look at followers numbers but only quality of work. Famous artists with big follower counts may have it a little easier, but that's no guarantee. Best way to figure out if a publisher will accept your work or not is to... actually submit it to publishers and see what they think 