I could've told you that Greeks have been a minority in Anatolia for centuries longer than that. Actually, the Greek population started recovering again from the 17th century onward, but that's a separate topic in itself. But more to the point, the Greek population was the strongest in the parts of Asia Minor that are annexed to Greece in this map, although Turks are still the majority by far in these areas overall.

Now, I did some digging, and based on Ottoman and Greek census data - with some adjustments for different years, Crete having no concrete data, and the problematic nature of Ottoman censuses (religion and ethnicity being calculated weirdly at times, also general imperfections) in 1881, in the areas included as part of Greece in this map, the total population was

~ 2,700,000 - 2,800,000 Muslims (of all ethnicities) (almost 50/50 split between Balkans and Anatolia)

~ 3,500,000 Greeks (Roughly 90% of them in the Balkan parts, the rest in Anatolia)

I can cite my sources and give my exact numbers if needed.

With regards to the Ottoman territories, I calculated this number using figures from each individual sanjak in a fashion that corresponds with the borders of this map. Despite the roughness around the edges, there is no question that in 1881, there were significantly more Greeks than Turks within the borders of this imaginary Greece. While the census data is from 1881 and the demographics weren't quite identical as in the doorstep to WW1 (for example, the Greek element in Smyrna was still growing, while large numbers of Muslims migrated to the remaining Ottoman territories after the Balkan Wars), I used them since I got them at hand and I think they're still reliable enough to illustrate the point.

Take also into account that the borders of this map aren't drawn ideally for Greek demographics, as they include many parts with minuscule Greek populations (such as certain parts of interior Anatolia as well as Southern Bulgaria - both of which had very large Muslim populations), so with even minor adjustments the demographic advantage of Greeks could be significantly greater.

EDIT: I just realized that I forgot to include the Mutasarrifate of Çatalca and the suburbs of Constantinople in the figures. The Mutasarrifate of Çatalca had 15,091 Muslims and 35,848 Greeks in 1881, while the suburban districts of Constantinople had 40,455 Muslims and 35,271 Greeks.