The US has been planning to have Julian Assange handed over for a longtime, that much is obvious. Mike Pence, the Vice President, was visiting Ecuador last year, notionally to discuss the Venezuela situation, and trade. But it was fairly obvious at the time, and even more so now, that they were discussing the details of Assange being handed over to UK authorities, and eventually extradited to the US.
In terms of quid pro quo, the situation is clear-cut – In February, Ecuador got a $4.2 BILLION loan approved by the International Monetary Fund (amongst other pay-outs). Reuters reported on February 19th of this year:
Phi Beta Iota: We have no direct knowledge but on balance we consider WikiLeaks a useful public service and the manner in which Assange has been treated to be reprehensible. Somewhere in here, truth will out.