Some Gents walking arm in arm in Punch magazine, 1843, identified as such in the caption:
GENTS — "Did you ever see such a rhinoceros!"
RHINOCEROS — "Vell, I never seed sich monkeys!"
The men's silhouette of this period in fashion plates is a fitted look, with a nipped waist in the frock coat (that might be enhanced by something like this extant 1842 men's corset/waist cincher).
But these Gents are wearing almost the opposite of that: huge paletot coats with large buttons and an A-line silhouette. Their check trowsers, patterned scarves, and buttons are also characteristic of their subculture (going by Albert Smith's The Natural History of the Gent).
Smith even has this tiny illustration of a Gent at the end of one chapter. You could spot this type of man from 50 paces with his loose coat and cigar.
Because all of my readers might not know this particular type of 1840s man, here's a refresher with illustration:
The first Gent we ever saw, we encountered on the roof of an omnibus, with his hat a little on one side, and a staring shawl round his neck. He was also smoking a cigar, as he sat next to the driver in order that he might reap the benefit of his anecdotes and remarks concerning the horses and vehicle, to which the Gent replied at intervals, "Ah," and "Yes," and "I should say not," and "Just so," with other similar phrases used to fill up unmeaning dialogue.
— Albert Smith, The Natural History of the Gent (1847)
A narrow-brimmed hat is referenced a lot, sometimes drawn ridiculously narrow as in the illustration with the "I'm a Gent – I'm a Gent" sheet music, also from 1847.
George Cruikshank absolutely included the Gent stereotype in his mid-century art, although he didn't really harp on the word like Punch. My beloved melodramatic temperance saga, "The Drunkard's Children," has Gents in a "dancing room" beneath a sign that warns, No Gent to Dance with his Hat on, No two Gents to dance together, No Gent to smoke except at Refreshment time.
(The Wellcome Collection)
Although "Gents" aren't a specifically gay subculture (and usually are depicted as pick-up artists seeking women), Gents dancing with each other is also referenced by Albert Smith, who condemns it in his Natural History:
Note—If ever you see two Gents dancing together at a bal masqué, you are at liberty to kick and insult them, with every opprobrious epithet.
In another 1843 Punch cartoon, an obnoxious young man wears a frock coat and not a paletot, but his loudly patterned trowsers give him away as at least Gent-adjacent.
A Gent can wear a frock coat, especially in the early 1840s, but by the end of the decade and into the 1850s he's known for his huge paletot overcoat—which is consistently called a paletot but isn't the more modern overcoat called by that name (and usually looks single-breasted with very large buttons?)