Yes he is overrated in some way, even tough I like his tennis. Gasquet is more talented than him but Murray is mentally stronger and has a good sense of tactic. It's mostly the British press that makes him out to be something he isn't (at least not yet).
Many people also believe the same as yourself, that Gasquet would beat Murray.. It's just opinion.
Also, based on playing abilities, many people believe that Andy is playing at a Top5 standard and would be so if he hadn't missed 3 months and 3 grand slams due to injury last year. This is one of the reasons people may have faith in Andy as opposed to Gasquet.
I can't believe I'm saying this (considering all the flak Murray has received, in the past, as concerns physical conditioning), but I think Muzza now has the edge over Gasquet in a longer match...the Scot looked pretty ripped in Doha, while Gasquet isn't the fittest, mentally and physically, imo.
But I still wouldn't go as far as saying Muzza is a "lock" in their potential QF match-up.
The Brits have a tendency to be apologetic about their athletes in general (British footballers "win a penalty" when they dive, for instance, foreign footballers are cheating bastards when they dive), and British media have a way of building up their sport figures, only to turn on them when they fail to live up to the hype. Murray's rated just fine outside the islanders I think.
Gasquet may be the more naturally talented of the two IMO, but there's only so much natural talent can do for you. Murray seems to have matured a lot lately, mentally and emotionally, and he's dealing with the pressure of expectations a lot better than Gasquet. Add to that, he is the better tactician (or so it's been demonstrated on numerous occasions) which pays off in the long run. If the two were to meet in the R16 however, it would mean they were both consistent enough to make it that far, and given their H2H (2:0 in favor of Richie), there's no reason to write off Gasquet so easily.