It is not that simple. At first, Kickstarter
charges 5% fees plus (depending on the country you are in) ~3% + 0.20$ from each pledge as payment charges (though the payment fees may sometimes be as high as 5%). So you end up with 8.something % less than you collected (with bad luck up to 10.something %). Btw: Shipping cost also count towards the funding goal and therefore also towrds potential taxable income and kickstarter-fees.
Regarding taxes this will be massively dependent from the country you live in. Typically taxes are based on your positive income on a yearly basis. As you have cost involved as well you typically won't have to pay taxes on the whole sum. The problem is that you have the income upfront whereas the cost will rise only later, after you got the money.
Obviously the easiest thing would be if you manage to produce and ship the goods within the same year that you collected the pledges in as in this case the cost and the income show up within the same fiscal year, therefor lowering your taxable income. If you do not manage to do so (as the Helix did) things start to become a bit more difficult - you may be able to shift income to one of the following years taxwise or to safe for expenses that will happen in the following years or to make use of expenses that already happend in the years before. Or you can make use of two or more different companies - one that collects the pledges that pays another one to create and deliver the goods. And so on and so on. What is possible or useful fully depends on the laws in your country and the creativity of your tax advisor if you have one. In some countries you may i.e. be forced to pay VAT on the pledges (which can be a fortune).
So in the end: Yes,
the pledges are taxable income. No, problably you won't have to pay taxes on the whole lot. Therefor the 40+% off for the pledges are probably wrong in most cases.
As for the Helix: They collected 2.26 Mio CAD which today equalled roughly 1.7 Mio US$ if I remember correctly. Minus 8.x% for Kickstarter and payment fees would be something like 1.56 Mio US$ left for 1136 bikes in various specs, including (expensive) worldwide shipping to various countries in most cases - on average 1370 US$ per bike including shipping. What amount of that goes to the tax office and when we don't know (or at least I don't).
One early Kickstarter-founder here in Germany did a writeup on his bitter experiences with the tax-office. As over here we probably have on of the most complicated and awkward tax-legislations worldwide it is probably more easy in every other country... The writeup is in German and hard to unterstand even if you are German, so I add it here for reference-purposes only:
https://www.magniclight.com/index.ph...4-crowdfunding