According to the Afterpay investor relations site, Afterpay's gross revenue for FY21 (ended June 30, 2021), assuming constant currency exchanges rates, was $978 million AUD [0]. If you subtract out the first half of FY21's revenue ($385.2 million AUD) [1], we arrive at an implied revenue of $592.8 million AUD for the second half of FY21. Convert that to USD (USD$1 = AUD$1.36) and we arrive at an annualized revenue run rate of ~$871 million USD.
Which implies an acquisition price of ~33.3x gross revenue. Which is certainly a lot better than 76x ratio. Moreover, that growth rate is ~53.9% ($592.8 million / $385.2 million) over the prior half-year which is truly astounding growth.
[0]: On https://corporate.afterpay.com/investors/asx-announcements, go to 'ASX Announcements', then find the 'FY21 trading update' dated 2 Aug 2021, $978 million is on the second data column of the second table on the first page.
[1]: On https://corporate.afterpay.com/investors/asx-announcements, go to 'ASX Announcements', then find the 'H1 FY21 Results Announcement' dated 25 Feb 2021, $385.2 million is on the fourth data row of the first page's table.