'em = uneducated or working-class English for 'them'.
gel probably = 'gal' (informal for 'girl'), said in any of 100s of non-middle-class accents. 'gal' is used informally to refer to both girls and women.
you was = uneducated or working-class English for 'you were'.

The dialogue is from:
English Folktales
'The Hole Stone'
http://adlitteramjournal.com/wp-content/uploads/2017/12/Ad-Litteram-Journal_December-2018_English-Folktales-World-Folklore-Series-.pdf

I didn't know that at all, actually! I'm completely ignorant when it comes to literature. At school I had to study English Literature (ugh!) as well as French Literature and Russian Literature (as part of my French Language and Russian Language courses respectively) and HATED all of the literature. In fact, I only read half the books! So I'm not a great expert on world literature.... However, this Hole Stone story looks almost interesting(!), so as it's only a few pages long I may even read it in full....

Gypsies, eh? That explains the 'uneducated/rustic' English which is used occasionally, eg
* 'when us Travellers gets married' instead of 'when we Travellers get married' etc.
Perhaps one way to convey this in the translation might be to include Russian gypsy terms/dialect from time to time – if Russian has a gypsy language/dialect. I'm not an expert on literary translation, though!

Thanks for the information and link, I'll try to read it!