It'll include positions for 1,692,919,135 stars.
Information about Gaia is available at http://sci.esa.int/gaia/
and about DR2 at https://www.cosmos.esa.int/web/gaia/dr2
According to the DR2 Media Kit, which is available at http://sci.esa.int/gaia/60174-media-kit-for-gaia-data-release-2/
The press event about the Gaia Data Release 2 is being organised by ESA at
the ILA Berlin Air and Space Show in Germany on Wednesday 25 April 2018,
The event will be streamed live at: http://www.esa.int/live