Fortnite Servers were down a few times this weekend with connection issues as well due to database errors. I played the "Save the World" PvE almost all weekend and had errors myself.
The shear volume of players that played PvP and PvE this weekend were insane. PvE had a new 25 quest line that took you through new AWESOME looking areas for some free phatty loot that is normally VERY hard to come by and PvP dropped leaderboards and cosmetics for characters.
At the rate in which Fortnite is growing PvP wise, it will for sure keep pulling in great numbers. Having their currency bounce between PvP and PvE, and making PvP players have to ether buy currency for cosmetics or actively play PvE is brilliant. It's injecting ALOT more life into the PvE portion of the game to get players to earn currency to spend in PvP.
PUBG is a phenomenon for sure that started this trend, but I do believe others like Fortnite will find their niche and perhaps come close to rivaling. The art style is beautiful, and I believe they will churn out content/updates/patches at a much faster rate than PUBG will and can.
Comparing the two though, there is definitely an audience and room for both. Some think Fortnite is better, some think PUBG is better, to each their own, but neither of those statements are fact. PUBG has the numbers right now, and I believe will maintain HUGE numbers for quite a while. As new games emerge that use this formula though, they will start giving players things that PUBG do not (ala building in Fortnite, which is awesome).
I am not a PvPer at all, and absolutely LOVE Fortnite PvP. I can jump in for 20-30 minutes and depending on how long I last, get multiple games in. Queues are quick, your jumping out of the bus minutes after dying, and your right back in the action. As a PvE'er, this is definitely a welcome addition to the game and gives me a break from the grind.