I’d guess the whole movie ends with a stalemate. Finn and Phasma seem to be fighting aboard the Supremacy – if that’s the case, the largest ship in the First Order fleet is going up in flames. Rey seems to get free from Snoke’s clutches. Hard to say where the others are, but it looks like they’re all at large. Hosnian Prime is still destroyed, D’Qar is destroyed, but the First Order has sustained substantial losses and the Republic still has fight left in them. So neither side really wins.
It’s hard to say to be honest as I suspect the ending will provide a catalyst for the next trilogy, so it could very well end with The First Order staying in control.
The resistance didn’t seem as though they had much of a hope in hell of beating the first order at the end of TLJ (and it remains to be seen how many others they will be able to recruit to their cause).
Having said that The First Order looked pretty disorganised too, so it could go either way.