I am Egyptian, age above 45. I have a Schengen visa. Can I enter Turkey after getting an eVisa, but coming to Istanbul from Budapest with Turkish Airlines and leaving Istanbul back to Cairo through Aegean Airlines?
Here is the answer of your question: Yes , you can enter Turkey with e-visa does not matter from where do you go to Turkey.
However, I guess you wanted to ask something else. Then I would suggest to: -Explain the situation better! -Did you buy the tickets separately? -Do you have a checked-in luggage? -Does Aegean Airlines directly fly to Cairo from Istanbul? -Do you have a multiple entry schengen visa, if you need to enter Greece?