Some pronounce it as it's written - [keit]. While he is [kit].
The surname is of Irish origin, and is pronounced as [kilben] in this country. While English commentators mistakenly call him [kilbein]. The Irishmen seem not to like it...
First, don't say it in English manner - [klaivert]. It's very wrong. Another wide-spread version [kluivert] is wrong too. The traditional spelling of this name is "Kluijvert", where "ij" is pronounced as French "eu". The same story as with Cruyff and Kuyt.
The surname of this German citizen of Panaman-Brazilian descence and with English name, of course should have been nothing else but Hungarian. As the rest of Hungarian 3-syllable surnames it has a stress on the first syllable. While "-nyi" is pronounced as [n'ї]. So, [koo-ran-yi].
The same rule as in cases of Cruyff and Kluyvert. The correct spelling should be "Kuijt", and correct pronunciation (a la French) - [keuyt].