Warriors were too good for Leicester Tigers at Scotstoun to book their place in the quarter-final, while Leinster underlined their tournament favourites tag in the 10-try thumping of Harlequins at Aviva Stadium.
Smith accepts Glasgow are underdogs but he believes the URC champions can produce a shock.
"Leinster are top of the log in the URC, they've got a squad with huge depth," Smith told BBC Scotland.
"They are probably the most talked about team in world rugby at the moment, so it will be probably the toughest task we've had in a very long time.
"Of course you must go there with a mindset that you can achieve on the day. Looking forward to a big challenge, but they are definitely the favourites."