According to Canons website the 600D (T3i), and everything else up to the 700D, is a camera for beginners, while the 5D3, 1Dx and 1Dc are the only 'professional' level cameras. Everything else is classed as 'enthusiasts' level cameras which is the 60D, 70D, 7D and 6D, but I've seen many photos in magazines, books etc. taken with so called 'entry level' cameras.
When used correctly any camera can be used to create exceptional images in good conditions. It's only when the conditions are more challenging that the higher level cameras come into their own. I've seen a pro, ie. getting paid to shoot, who have a 550D and Tamron 28-300 VC, a couple of lights and a backdrop at a few local events doing 'on the spot' portraits and printing them out on an Epson R300 printer.
I've been told I wasn't allowed to take my 550D and 13-135 into a gig recently, but have just had permission to take my 5D3 with Sigma 24-70 f2.8 and Canon 50 f1.4 into a gig around 300 yards up the road.