"g" in German is always pronounced like in "gig".

Aha!

So then why haven't etymologists latched onto that German word "giga" as a source for the word "gig"?

Is it because they think that the early jazz musicians might not have known that German word? But as PoppaGator wrote in that post of his that I added to this thread, a number of early jazz musicians were educated, and some may have been educated in Europe and so may have been familiar with that German word giga" and may have popularized it in New Orleans and elsewhere, using it as a short cut way of referring to a short term music job.

I'm not saying that it's actually the source of the word "gig", but I'm wondering why the "High German "Giga" music instrument" rarely appears to be mentioned in articles about the source of the word "gig".