My sub gap between the two isn't extremely pronounced; I've 344 subs on WEBTOON, as compared to 280-ish subs here on Tapas. That said, I got promoted on 'New From The Community' here on Tapas, while I've never been promoted on WEBTOON. That, plus the fact that I'm very active here on the forums, helps keep the numbers close.
I expect the WEBTOON version to pull further ahead in time. I put most of my marketing efforts into the WEBTOON version as well, since, like a lot of artists, I'd love for future series of mine to attract the right attention from the WEBTOON staff, and potentially become featured series.