PantTwizzler - from the Oxford website www.ox.ac.uk/admissions/undergraduate/courses/admission-requirements/uk-qualifications?wssl=1#
GCSEs will be taken in to account when we consider your application but they are just one aspect that we look at. GCSE results will be considered alongside your personal statement, academic reference, predicted grades and performance in any written work or written test required for your course. If you are shortlisted, your performance in interviews will also be taken into account.
Higher grades at GCSE can help to make your application more competitive, and successful applicants typically have a high proportion of A and A* grades or 7,8 and 9 grades. However, we do look at GCSE grades in context. Where possible, tutors will be made aware of the overall GCSE performance of the school or college where you studied. They will also have information on how you have performed compared with other Oxford applicants at similar schools. (See further information on how we use contextual data.) Tutors will also consider your achieved or predicted grades at A-level (or other equivalent qualifications), your personal statement, academic reference, and any written work or written tests required for your course. If your application is shortlisted, your performance at interview will also be taken in to account.
It doesn’t specify number of GCSEs taken, just that proportion of top grades be high, which for your DS appears to be the case. You’d want to check what it says for a specific course, but it doesn’t sound like cause for concern. 8 sounds like a great number to have taken - my school encouraged me to take some exams a year early, then the following year made me take bullshit exams so I wouldn’t have free periods (Drama GCSE, French E(xtended) Level, and Maths Pure 1.) What a waste of time.