Wales find themselves four points behind group leaders Ireland after their 1-1 draw with Serbia on Saturday, but Vokes still believes that Wales can qualify for the 2018 World Cup in Russia.
"It's early days and we're still well in this group," Vokes said after the game.
"We're only four games in, so there's a lot to play for.
"But this result does make that Ireland game more important. I wouldn't say it is must-win, but it is a massive game. If we win there it will open the group right up".
Wales were 1-0 up leading into the last five minutes of normal time against Serbia and Vokes says that Mitrovic's late equaliser was a "bitter blow".
"It was a bitter blow at the end but we looked really good going forward," Vokes added. 'We'll go to Ireland full of confidence because we've obviously done well recently.
"We know we've got to deal with the expectations now coming on the back of the summer.
"I think we have done that, we've just got to come back now and focus on the game in March".