Obviously none are perfect anologues, and shouldn't be, but it's still fun to spot the influences.
Breton - British/French (maybe the most perfect anologue, from the pagan primitives to the cultured civilisation and perfectly british appearance)
Imperial - Meditaranean (italian, spanish, greek)
Nord - scandinavian
Redguard - Sub-saharan African people with middle eastern/japanese culture
Dunmer - Tough one but I think a little bit indian/chinese, with a lot of alien on top. The way they're treated badly and work hard as merchants and etc seems very indian/chinese.
Altmer - German (aryan supermen anyone?), french and jewish (contradictory to the german, but yeah)? Maybe a certain swiss elitism.
Orsimer - I honestly see orcs as the anologue for primitive tribal cultures, their advanced smithing and armour being the only contradiction which is perhaps mongolian/russian inspired, but primarily I see them as an homage to tribal west africans, polynesians and melanesians. Melanesian highlanders especially with the tribal chief having multiple wives and selling off women with a dowry/bride price, not to mention the powerful build, the living in the mountains, the alchemists, the seeing-red berserk mode even, common practice for PNG highlanders to take a drug that makes their mouth and eyes red before going crazed into battle.
Bosmer - british peasants mostly, with some american indian (north and maybe more so south) aspects to their culture
Argonian - Maybe also british peasants, australian convicts? South american shamans with the drug abuse? All a stretch, they don't give me a solid vibe to be honest, I don't feel like they match anyone that well.
Khajit - middle eastern/gypsy