A British newspaper report on Wednesday suggested that Miller, 32, a former Rangers team-mate of Queensland captain Craig Moore, was set to reject offers from Scottish clubs Dundee and St Johnstone to sign a Roar contract next month.
But a cautious Farina said a deal was far from settled.
"I've been talking to him, we're going to get him out here and there's a chance he'll sign, but nothing's definite yet," the coach said.
"It just depends on what he wants to do. I just don't know.
"We're still looking elsewhere. We're not going to put all our eggs in one basket."
But Farina acknowledged it was a "positive" that Miller, who most recently played for battling Belgian second division club Lierse, was willing to travel to Australia to contemplate a permanent move here.
Farina warned Queensland fans not to expect miracles from Miller if he did sign for the Roar.
"We can't get mistaken - Charlie Miller's not going to score 20 goals for us," he said.
"But he's a player who I think can bring something to the league."