I record 8 hours of audio and when I export, it is 5g in size and only 2 hours recorded. Anyone help?
Windows 8.
I’m guessing that you are exporting as a WAV file.
The WAV file format has a size limit of 4 GB. For very long recordings it is necessary to use a different format, such as FLAC or MP3, or split the recording into a series of smaller files. (this article could be helpful: https://manual.audacityteam.org/man/splitting_a_recording_into_separate_tracks.html)
Note also that many USB thumb drives also have a file size limit that may prevent saving very large files.
What format did you export to? There is a 4GB file-size limit for WAV files. (Most other formats don’t have “artificial” limits.)
You might be able to export a larger file but unpredictable things can happen when you try to play it because the file-size field in the header will be fouled-up.
…But, nobody wants to listen to an 8-hour recording anyway. 
(You might want to break it into shorter files.)
As above, even if you do force it to work, it may not work if somebody else has to play it. Departing from standard formats is dangerous.
And a note: MP3 files create sound damage and it gets worse as you edit them. Not recommended for production.
Is this your podcast? Who is your target audience?
Koz