Guitar Pro multi-track editor and music composer is able to export both the tablatures but also MIDI audio from any of their projects (regardless the version). You will have have to use the original software in proper version if you hope to convert (export) gp5 to midi.
Convert Guitar Pro 5 project to MIDI-sequention sound.
We found 2 software records in the database related to .gp5 to .midi file format conversion.
Microsoft Windows software - convert gp5 to midi on Windows
Multi-track editor and music composer for guitars
Convert from gp5 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned gp5 to midi. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert gp5 to midi on OS X
Mac version of the popular tablature editor