No one can tell you if your daughter will get an offer or not. If she wants to go to Oxford, she should apply and put herself through the process and see what happens. All the stuff you and others have said - her (for Oxford!) lower GCSE scores in relevant subjects may count against her in a strong field; MFLs are one of the less competitive subjects to get offers for. No one can say how all of that will pan out, or how she will do in the interview if she gets one. As others have said, she could contact the college(s) she is interested in and ask if her GCSE results would likely mean she wouldn't make the cut. No one here can tell you anything other than the published previous admissions statistics and anecdotal experience.
As others have said, if you're applying to Oxbridge (or other competitive unis, especially for competitive courses), it is a good idea to have other options you are excited about and would be happy to go to.
As for relevant(ish) anecdotes, here are mine:
Nephew has an offer to do MFL at Oxford. He got 9s in all GCSEs apart from an 8 in History (state school). His best friend had slightly worse GSCEs (couple of 8s, one 7, I can't remember what in) and didn't get an offer.
DD is a second year medic at Oxford. (She is pretty exceptional academically, even in the exceptional academic field she is in now and got top scores in all her GCSEs and A Levels.) She works hard, but also has a lot of fun - plays sports, goes out drinking, goes to London for gigs and football. What she doesn't ever do is come home in term-time - we live on the south coast and my nieces who are at Glasgow and York come home more than she does. Having said that, one of her fellow medics goes home to Bristol every weekend, so it can be done. Her friends are a mixed bunch - some extrovert, some less so; some work extremely hard and live and breathe their subjects, others enjoy their subjects but not as much as they enjoy taking the afternoon off and sitting in the pub!
Finally, I did MFL at Oxford (obviously quite a few years ago, but having seen my nephew's reading list it hasn't changed all that much!). It is very heavy on literature and I would advise anyone considering MFL at Oxbridge to have an honest think about if the course is for them. I loved it, but there were definitely people who really didn't!