There is no up-to-date official Debian package for GHDL.
Unofficial ghdl-0.33 packages are available for Debian 8.2 (Jessie) and Ubuntu 14.04 LTS.
The packages can be found in the Sourceforge Files section:
https://sourceforge.net/projects/ghdl-updates/files/Builds/ghdl-0.33/debian/
Download the binary package for your architecture.
For Debian jessie 64-bit, download ghdl_0.33-1jessie1_amd64.deb.
For Debian jessie 32-bit, download ghdl_0.33-1jessie1_i386.deb.
For Ubuntu 14.04 64-bit, download ghdl_0.33-1ubuntu1_amd64.deb.
Then run the following command to install the package:
sudo dpkg --install ghdl_0.33-1jessie1_amd64.deb
In case you want to build your own binary Debian package, the Debian source package files are also available in the Files section. If you want this, you probably already know how to do it. (Or read http://debian-handbook.info/browse/stable/debian-packaging.html)
Alternatively, you can download the plain source code release of ghdl-0.33 and build GHDL from source on your own computer. This will keep GHDL outside the context of the Debian packaging system. In this case, make sure that Debian packages for LLVM, Clang and Gnat are installed, then follow the instructions from the README file in the GHDL source directory.