The former Anfield star also says the Europa League could prove a hindrance to their Premier League hopes.
The Belgian was signed from Aston Villa in a big-money move during the summer transfer window, tasked with scoring the goals that the side were so sorely missing last season.
He has had a slow start to his Anfield career so far, with a goal against Bournemouth, which should have been ruled offside, his only effort to date.
Many are expecting him to be a big player for the Reds, though, and Souness is one of them, saying he could become a talisman for the Reds.
"He has the potential to be an absolute star," Souness told Sky Sports.
"If he's fully fired up and motivated, he could take the Premier League by storm and be a superstar at Liverpool. But if you have a Benteke who picks and chooses when he plays well then it might not be good enough. A lot of Liverpool's success this season will rely on Benteke."
Europa League a hindrance to Premier League campaign
Despite struggling, the Belgian is still likely to be leading the line in the Premier League and Europe, namely the Europa League, this season for Liverpool.
Brendan Rodgers' side have their opening continental tie against Bordeaux to tackle once they deal with a trip to Old Trafford to take on Manchester United, with it not yet sure how the Reds boss will approach the competition.
Rivals Everton suffered last season as they struggled to marry Europe with domestic duties, and Souness says it is 'not helpful' to a Premier League campaign.
"It's not helpful for the Premier League campaign," he said.
"You are playing catch up all the time. Sometimes you're playing on a Sunday knowing the teams around you won on the Saturday and you know you have to win to keep with them."