All you need is the Bitcoin Wallet Address that has been set up by Wikileaks to see how much the fund has raised. And while it is indeed growing rapidly, as of around 10AM EST on 4/12/2019, the wallet only had about 6.3 BTC in it (about $31,000 USD); that may afford the Wikileaks founder about a week of representation by a good law firm.
Donations began pouring in during the 24 hours following Assange's arrest. It represents a demonstration of financial support from the libertarian Bitcoin community, which has had a strong link with Assange and Wikileaks for nearly a decade. Wikileaks was one of the first organizations to start accepting Bitcoin, which it did in 2010, after traditional pay services like PayPal and Visa withdrew support.
The Wikileaks Defence Fund accepts donations in a number of non-traditional currencies, including Bitcoin and Zcash. Those wishing to support can also donate by sending money via bank transfer, MasterCard, Visa, Amex and Discover.