Technically yes, but the agreement has been in question since November last year, when the DUP abstained on a Finance Bill, to indicate their displeasure with (then) May's Brexit approach.
The DUP has abstained from supporting the Government in a Finance Bill vote, calling into question its confidence and supply agreement with the Conservative government.
Speaking on BBC Radio 4's The World Tonight programme on Monday night about his party's reasons for doing so, DUP MP Sammy Wilson hit out at Theresa May's Government for failing to honour its side of the agreement.
"The Government has seriously broken an agreement it made with us when it came to the Brexit legislation Northern Ireland would not be treated differently to the rest of the United Kingdom," said Mr Wilson, noting his view was evidenced by the resignation of former Cabinet Ministers Esther McVey and Dominic Raab.
"Since the Government has not honoured its side of the bargain we tonight tried to spell out some of the consequences of that being broken."
As a reminder, the agreement included an obligation for the DUP to support Finance Bills, among other things:
The confidence and supply agreement reached between the DUP and the Conservatives in June 2017 states: "The DUP agrees to support the government on all motions of confidence; and on the Queen’s Speech; the Budget; finance bills; money bills, supply and appropriation legislation and Estimates."
Johnson formally nixed his majority in September this year by expelling the 21 Tories which supported the Benn Act (that eventually forced Johnson to send an extension request to the EU). So it's a bit unclear what if any relevance the supply agreement with DUP had after that, since Johnson has been seeking to force an election since then, which insofar he was no able to get because of the hurdle presented by the Fixed Term Parliaments Act.
And as you observed, the DUP also opposed the deal that Johnson negotiated with the EU:
Mr Dodds accused Mr Johnson and other government ministers of not knowing "what on earth" they had negotiated as part of the revised withdrawal agreement with the EU.
He said the plan, which would see NI businesses having to fill in exit declaration forms on goods going to GB, new checks on goods crossing the Irish Sea and extra administration, as "the worst of all worlds".
As another reminder, the 2nd reading of Johnson's Withdrawal Agreement Bill did pass despite DUP's opposition. It was only the accelerate schedule that sank because some the Labour defectors didn't support the schedule, and neither did some of the expelled Tories (who also voted for the 2nd reading).