I don't research the software side of things too much, but I would assume that the amount of games doesn't matter as much as it does the amount of games in a genre that the player base of a console supports.
The PS4 might have more games than the Xbox One, but depending on the genre of said games, those 20% more games on the PS4 might not drive consumers to purchase them because it (genre) does not fill their needs.
While on the Xbox One side, while having less games overall, what it does have in plenty is shooters. Xbox owners love like 2 things, sports and shooters, so even with less games overall, because the core base of Xbox favors shooters (and sports), they'll pick those up in spades, while another genre (JRPG) is almost ignored on the platform.
As long as the player base of the console gets games in the genre that is favored the most, I think the tie ratio will be "good".
Or I can be completely off base with this.