I've heard both by many different people, some place the pressure on the "t" in Qatar and some elongate the first or second "a" to some extent.

I haven't found that the way of pronouncing is tied to any specific native langugage by the speaker.

Personally I have always used the "Qa-taar" way, by elongating the second "a".

I found it more funny that the guy doing the interview spoke of "Do-haa" with an elongated "a" there.

-A