Can someone live outside Israel and be a Zionist?

Quite easily.

Being a Zionist only means one thing: Believing that the Jews have a right to an independent State and that this State should be in the Land of Israel. A person can hold this belief regardless of whether he is in Israel or not and can disagree with this belief regardless of whether he is in Israel or not. The largest group of Zionists (numerically) are American Christian Zionists.

There are three reasons why non-Israeli Zionists are more visible than Greek Nationalists or Turkish Nationalists operating outside of their home countries.

1) People believe that Zionism is something other than the definition given above. Usually people incorrectly use Zionism to refer to the Anti-Semitic depictions of a worldwide Jewish Cabal or some other conspiracy theory. However, that is not what Zionism is.

2) The State of Israel was a national state created by the Return of a People to their Native Land as opposed to the Greek and Turkish States which were created roughly where each group already had a majority. As a result, it required a huge initial demographic shift.

3) Israel is a more "controversial" state than either Greece or Turkey because more countries use hatred of Israel as a release valve for their citizens' hatred of their own government's poor record.