Mr Russell said the campaign was “moving on from hope to reality”, as he opened the SNP spring conference in Edinburgh.
His address came as a new YouGov poll in The Times put support for Scotland leaving the UK at 49%.
Mr Russell told SNP activists: “Our campaign is far from won, but today we see independence support is at 49%.”
The UK Government is “running scared”, with its refusal to grant Holyrood the powers for a second referendum, he added.
Mr Russell hit out at Theresa May’s Tory administration branding it “the most intransigent, the most arrogant UK Government ever”.
Meanwhile, he said the “poisoned policy” of Brexit would “deliver a devastating blow” to Scotland.
“It will destroy thousands of jobs. It will, by driving away talented and welcome EU citizens, undermine whole industries and increase depopulation in our rural areas,” Mr Russell said.
“Brexit is not the only reason for change in our constitutional status, but it is a massive object lesson in the continuing failure of an archaic, deeply divided and out-of-touch Westminster system which looks, sounds and is well past its sell by date.”
With First Minister Nicola Sturgeon having outlined plans for a second vote on independence before the next Holyrood elections in May 2021, Mr Russell cautioned: “The journey for any nation to independence is never easy or straightforward”
But he insisted Scotland was “moving inexorably” towards that.
Mr Russell, who described the independence referendum of 2014 as having been a “unifying experience”, stressed the need for the SNP to listen voters to build support.
“We need to encourage everyone who lives here to play a part in building our new national story,” he told the conference.
“We won’t do so by ignoring them, or by insulting them, or by challenging them in ways to which they simply cannot respond.
“We will only do so by working with them and listening to them because in so doing we will all become stronger”.
The plan for a citizens’ assembly for Scotland, announced by the First Minister on Wednesday to consider issues surrounding the country’s future, is “a radical new initiative”, Mr Russell said.
“It will allow Scotland to engage with its future in a constructive and thoughtful way,” he added.
Mr Russell continued: “Our common cause here is independence. Our common aim is to achieve it. There is a democratic pathway towards it which ensures that when we get there our effort will be internationally accepted.
“And there are ways in which we can unify Scotland around that vision. The pathway is broad. We need to walk it with all our fellow citizens.”
He added: “There is a distance for us still to go, but we have come a vast distance already.
“Further, if not faster, than was expected in that bleak time. But we have to finish the journey.”