Is there any benchmark number of people in such a community which is the minimum required for a successful crowdfunding campaign?
Some studies on crowdfunding:
"How do we study crowdfunding? An overview of methods and introduction to new research agenda", by Agata Stasik and Ewa Wilczyńska - Journal of Management and Business Administration Central Europe, Vol. 26, No. 1/2018, p. 49–78.
"Dynamic Strategies on Firm Production and Platform Advertisement in Crowdfunding considering Investor’s Perception", by Ying Ji, Ju Wei, Zhong Wu and Shaojian Qu - from an article in Discrete Dynamics in Nature and Society 2018(1):1-12.
"Which updates during an equity crowdfunding campaign increase crowd participation?", by Jörn Block, Lars Hornuf and lexandra Moritz, Small Business Economics, January 2018, Volume 50, Issue 1, pp 3–27.
After reading those papers I offer this advice:
You'll probably want to obtain more followers first. If you need ₪ 50000 (Israeli New Shekels) for the first year and each follower donates an equal amount (an unlikely example) that's only 31.25 each (U$8.51).
The current business model is that everyone gets something for free, while it's difficult to predict how many would want to pay if it's only 10% (which seems optimistic) then you want those donators to come up with ₪ 312.50 (U$85.10) each. Look at it from your own point of view: There's a great website somewhere, how would you feel about shelling out ₪ 400 (U$100)?
It is my opinion that you would want ten times as many followers. That gives you a larger network where the group has much greater access to more people whom might also be interested and reduces the investment (or more accurately donation, the giving away of money) by tenfold.
The less you ask for and the more you offer (at this unidentified website) the greater proportion of people whom would be willing to chip in, ask for a lot (and what you offer isn't clearly great) and the donors will drop considerably; requiring an even greater expectation of each interested person.
Many campaigns rely on the "angel in the cloud" where someone comes along at the last minute and makes a sizeable donation, pushing you over the top. Needing that from the start seems like a recipe for failure.
You can obtain more accurate statistics by polling your readership. Ask how much each is interested in donating, example amounts: 0, 1, 5, 10, 20, 50, 100, 200, more. Once you establish the interest in paying and how much you might expect you'll have some numbers on which to base your decision to proceed with a crowdfunding campaign (you don't want a bumpy road or to lose inertia).
At the moment it would seem that the readership, or more precisely membership (you don't know the engagement level) of 1600 people is too low for the amount of funding you feel that you require to get the ball rolling. Perhaps encouraging qualified authors to write for the exposure that they would receive (rather than financial rewards) might be the route to go, to improve your site and increase the readership.