That's a fairly complicated answer. Most creators here are giving the simple response, about 5,300 impressions to receive $1. However your question was views, not impressions. We will do our best to answer that.
All things being fair, 1 view would result in 2 impressions, however that's not the case. Adblock users result in 1 view and 0 impressions. Also mobile users result in 1 view and 1 impression. Sometimes ads don't load at all on the mobile format due to insufficient supply, so again, 1 view and 0 impressions. Because of these reasons no one will ever achieve a 1:2 ratio.
We did some advertising on Project Wonderful this month so most of our visitors were desktop users. Consequently our ratio is going to be higher than a series that is featured a lot on the mobile app where readers are using the app and only seeing half as many ads. Also our visitors were seeing our ad, so obviously they don't have adblock turned on. On days we were advertising to non-adblock users on Project Wonderful, 1 view yielded 1.82 impressions. On days were we were not advertising to desktop users, 1 view yielded 1.52 impressions.
Since most here aren't buying ads, 1.5 is probably a more accurate value. So in that case, 5,300 impressions requires 3,500 views.
However, because Tapas is taking 30% of all ad revenue in order to support their servers and ad logistics, the take home pay is actually 5,000 views to earn $1. So in order to withdraw $25, you would need:
125,000 views
So if you look at any series total views and divide by 5,000 you can get an idea of how much that creator has made on Tapas. For example, Silent Horror has brought in about $7,140 as the most viewed series on the site.
What we're getting at is that ad revenue isn't the way to make money here at Tapas. It's just a little bonus. Tipping is much better, if readers are able to access free coins on an easy and consistent basis. But mainly Tapas is about building an audience large enough to support a pre-order and then making a significant profit on selling books and merch via Kickstarter to your audience, such as $127,000 in single use monocles.