On hards, he was absolutely faster. Got the gap down from over 9 seconds to about 3.5 seconds in about 15 laps.
Had HAM not lost 5 seconds going off track, he would have absolutely been in RUS' gearbox. Whether he would have passed him on track, who knows.
RUS did not have good pace on those hards which is why his engineer offered a late pit stop at the cost of track position.