Wow. I thought even a hint of Jewishness (see below) was enough to get citizenship straight away.
How long has he been in office? Because there are already quite a few Ukrainians skating for Israel.
CaroLiza_fan
He's been in the position of Minister of the Interior for less than two years. The Minister during the time that Isabella teamed up with Ilia would likely have been more liberal w/respect to immigration, but the makeups of the Ministries change quite frequently in Israel.
I'm not an immigration specialist, but in order to obtain citizenship I think you basically need to fulfill one of the following:
1. Have proof of at least one grandparent that is matrilineally Jewish (or I guess maybe Jewish by conversion)
2. Be married to an Israeli citizen
3. Be the child or immediate family member of an Israeli citizen
4. Go through formal conversion to Judaism yourself
5. Be working in the country for a very, very long time.
6. Receive refugee status
There are additional caveats of course (not deemed a security threat, not actively practicing a faith other than Judaism), but those are the basics.
I imagine the skaters from the former Soviet Union who have represented Israel at the Olympics fulfilled one or more of #s1-3. Tkachenko, may very well have Jewish ancestry, but in some circumstances this could be very difficult to prove, e.g. if his Jewish grandparent was not marked as 'Jewish' on their Soviet identity documents. Many of Jewish ancestry in the Soviet Union actively sought to hide their ethnicity due to fears of antisemitism.
Anyway, that was a much longer response than you wanted, but there you have it.