The youngster is currently on-loan at Plymouth Argyle.
Gray's deal at United expires in June and the told the Scottish Sun: "Darren was always a player who was going to be good enough, even when he was 16.
"He had a few injuries and had to keep battling away, but there was never a doubt he would make it. He got a bit of stick at first, perhaps because he was an easy target for the fans down there - but he's won them over.
"Darren's also really good with the young lads. With me being Scottish he's maybe a wee bit biased towards me.
"We're from the same area so he's always there if I need to speak to him.
"Before I signed my last contract he spoke to me and gave me a bit of advice which was great. My United deal's up at the end of the season so I'm just trying to get as many games as I can at Plymouth and take it from there.
"I'm 21 now so I need to be playing as often as I can.
"But getting into the first team at United is not easy and I'd been playing a lot of reserve football.
"I had the opportunity to go back to Plymouth so I took that to try and get as many games as I could.
"When I re-joined Plymouth they hadn't won a game in seven or eight, but we've won the last two and we've turned it around a bit. If I can do really well then hopefully I'll get a chance at United when I go back."