Well, things have changed in a couple months too, but in the 2.5 years I was on YouTube before they changed monetization to needing 1K subs, I earned just over $60. That was with less than 300. So 3.3x that, I can see $50 being pretty easy, so long as the views scale with sub count.I have focused more on growth than monetisation, but I would not call it easy to make $50-$100 a month with 1k subs. You probably need to do a decent amount of work to get there. Its been 8 full months since my channel reached 1k sub (hoping to reach 2k this weekend). During the 8 months I have earned over $50 a total of 3 times and 2 out of 3 are November and December when the add revenue is much higher than the rest of the year. 4 of the 8 months was sub $30 and I have never been close to $100 (my best month was $78.23).
I'm not complaining, 1k subs is defiantly a good foundation to build on and my channel is growing and hopefully making $100+ a month is not to far into the future, but to make $50-$100 month with 1k subs you most likely need to do a decent amount of work, at least if you don't do anything extra other than the ad revenue. The exception is probably if you are in a niche that pays extremely good or your niche is really popular right now so you get a abnormal amount of views.
My main point though is that, at 1K, you have a large enough audience that there's going to be a few, even if less than 10, who will donate, support on Patreon, buy your merch or use your affiliate links. None of those things require much work and once you set it, you can "forget" it, so to speak.
That, plus ad revenue? $50 is a good amount