I was reading this article: https://segmentnext.com/2018/07/31/nintendo-switch-sales-2/

And they stated that since Xbox One sales should be arround 45 millions units sold and be close to 56 millions by the end of the year, there is no chance Switch's 19,7 millions could reach Xbox One level sales.

We are here on VGChartz, which obviously doesn't have the same sales numbers at all (for Xbox One). According to VGC, Xbox One sold 38.4 millions since november 2013 while Switch sold 19.3 millions since march 2017.

So, do you think the Switch will surpass Xbox One sales before the launch of the Xbox Scarlett ?

At the rate it's going, it'll only take another year and a half (let's say Jan. 2020).

I could see the switch outselling the XBO by early 2020 if Xbox sales continue to pick up then maybe by Holiday 2020 which is when the next Xbox is rumored to come out.

Yes, by January-Feb 2020.

Are there actual proofs that XOne is above 40 millions?

It will depend on many factors, though it definitively seems plausible. The XBOne won't have good legs once the succesor is out, and the Switch is pretty flexible hardware, and Nintendo could just make as many variations of it just like they did with the DS.

Mid 2020 easy, perhaps end 2019. Switch is going to surpass xbox whit no problems.

That article makes no sense, it says Xbox One was around 30 million at the end of 2017 but 45 million in mid-2018, must be a typo and mean 35 million.

More than likely.

The Xbox One is going to be replaced fairly soon, probably next year. Switch will be around for at least another 4 years.

Switch isn't even a year and a half old and it's already sold more than half of it's sales. This is Switch avenging Wii U from how quickly Xbox One overtook Wii U sales despite a year lead.