Hi,
I installed ubuntu amd64 gutsy. For 64 bit version there are no xine support so I would like to switch to other engine probably to gstreamer.

Gstreamer is installed on my system. amarok, amarok-engine is also installed. BUT there are no "amarok-gstreamer" package and no way to change engine in amarok settings interface - only one option is available - xine.

How it is possible to solve this problem?

There are more engines, but the xine one is the best. Have you tried the Helix engine?

gstreamer support for playback was dropped with the 1.4.X series.

Xine exists for amd64.
I don't know, why it's not included in your distriubtion.