Sure. You can't measure it.
But manga is vastly more mainstream now outside Japan than it was in 2012-2013. You have a far larger number of people now getting into manga and anime than you did in 2012-13.
You had to rely on fan scans and translations for new releases. And a lot of the times back then, forums like this were how people got informed. Whereas now, you have official ways to read manga for free and there are tons of people spreading anime/manga news on twitter and other social media platforms.
It's definitely more logical to assume SxF in 2020 is more popular (outside Japan) than AC in 2013.
Spreading anime relies on the presence of an anime, SxF has none, and news relies on people spreading news about series they read, SxF is still niche and has few if any readers even among the more mainstream casual people carrying weight and clout. Even a search on youtube brings up 0 prominent youtubers generating any Spy x Family exclusive video with any meaningful number of views, Even prominent sites like ANN and other ani-manga news sites has few if any articles on SxF, and the one non manga/anime site it got mentioned on has little if any reception or noteworthiness, look how little
reception the tweet even received. It is hard to see how Spy x Family is popular outside of hardcore jump circles when it has little to no presence thus far in time.
And for places to read SxF, again mangaplus is a new and niche site (low page views), many people still dont know about it or read manga there (why are most screenshots from people on twitter, still non official versions of mainstream mangas, or
rehosted ones from manga aggregate sites, and not the mangaplus one?).
New people getting into manga and anime, wouldn't come anywhere close to SxF as theres no one speaking of this manga to bring it up to them, no one is adding it to listing articles (example "So you liked [insert anime] on Netflix, here's 10 other Japanese series you should check out").
I don't think it is logical to assume SxF is more than a middling niche series outside of jpn at this point in time as the data available really suggests otherwise and could be argued to be less popular than AssClass was in 2012.
