I'm actually less interested in if it's true or not (though it would be nice to know) and more interested in how a historian could verify such a claim. It's not like people were signing a form saying why they were buying the TV for. I imagine you could see the ratings for different programs and extrapolate from there, but that doesn't seem much rigorous
Without answering the question if this statement is true or not, the question of if this assertion could be proven or disproven does have an answer.
Since the late 1930's a company called Neilson Media Research has tracked the listening/viewing habits of viewers in order for media companies to know what has drawn the most viewers and therefore allowed them to decide on which shows to continue making and which where they could charge the most for advertising dollars.
At first Neilson ratings were done via a viewer diary. Where each member of the family could mark down what they watched and when. Starting in 1954, the Neilson company began providing research for local markets as well. Becoming a "Neilson Family" was such a cultural phenomenon that it entered our lexicon as both being an influencer as well as a representation of "Middle America".
Now mind you, in the 1950's the television market was QUITE different, and while we think of ABC, CBS, and NBC, being the big networks, there were others that competed such as The DuMont Television Network, or Metro Media, and one of their regular broadcasted shows was live wrestling! In fact, local programing via local broadcasters even if affiliated with "The Big Three" had gaps in the programing that they filled with local shows as varied as local news to "Fright Night" features and re-run movies. Amongst those were local sports such as professional wrestling.
Now, can I answer the question the "Did Gorgeous George sell as many televisions as Milton Berle?" Not right away I can't since I don't have access to the local TV ratings for the stations that carried professional wrestling, but it's important to note that Gorgeous George's televised career lasted into the early 1960's, while Milton Berle's popularity steadily declined. Additionally, because professional wrestling was largely a "local" program or a syndicated program and wrestling was in its "Territorial Era" before consolidating around large brands such as WCW and WWF, it would require a LOT of research and for a significant portion of both Milton Berle and Gorgeous George's career there was no research done on local market viewing.
Gorgeous George was a very popular wrestler, a kind of Lady Gaga of the wrestling world in the late 1940s, early 1950s. The professional wrestling world in those days. like today's WWE, was a mainly theatrical production. The wrestlers were self-created characters, playing roles in a relatively small number of plotted contests involving much tossing of bodies, heroes and villains, heroic comebacks and noble efforts, etc.
My father, like many, was a big fan of this "sport" and often took me to matches when I was 8 to 11. Why my mother let him do this, I have no idea. But I thought the matches were real. I rooted for the heroes and against the villains, and watched with dismay when my heroes were "hurt." I remember talking to one of them between matches, worried that he'd been hurt by a particularly vicious wristhold. He pluckily assured me that he could continue.
Anyhow, in this world of bizarre personalities, Gorgeous George was among the best known. His antics filled the arenas and inspired much shouting and cheering. When wrestling came to TV, c. 1948, many fans bought sets and relaxed on the living room couch, beer in hand, and watch their favorite muscle-bound warriors in combat . Uncle Milty appeared on our tiny screens at about the same time and he had a wildly faithful following, which tells you a lot about the overall quality of TV programming.
In these years, I think most TV purchasers were drawn not so much to George or Milty, but to the phenomena of television, remote viewing of distant events. TV watching was often a social affair, with friends or family sharing the experience, in awe and delight. Whether what you saw was good or bad didn't matter much.
How you could ever quantify which performer sold more TV sets, I don't know. My father was a furniture dealer and he SOLD TV sets in his store. As a ten year old who often hung out in the store, I sold some myself. I don't remember any customers saying they were buying sets so they could be sure to see Gorgeous George or Uncle Milty, Or even Howdy Doody.
Getting a television set in my house when I was ten gave me an unquenchable yen for gadgets like transistor radios and electric razors. It led me to buy my first computer in 1979. And as I remember, I became a redditor in about 2007. For the curious among you, I am 83. I was born in 1937. Not all of us are dotards.