I've read on various web sites that in English, some people pronounce the word "geisha" as "geesha", and that it's a mispronunciation.
For example, from Wikipedia:
They almost exclusively serviced American GIs stationed in the country, who referred to them as "Geesha girls" (a mispronunciation).
Shortly after their arrival in 1945, some occupying American GIs are said to have congregated in Ginza and shouted, "We want geesha girls!"
(I haven't checked the citations, as they seem to be books about history, not language)
and from a blog post at Nubui Kuduchi:
mispronounced, as it often is today by the average person on the street, as gee-shah, not gay-shah
Whether "geesha" is a valid pronunciation in English is outside the scope of this stack exchange, but I'd like to know whether it's a valid pronunciation in Japanese.
The hiragana of "芸者" is "げいしゃ". According to How 「えい」 should be pronounced in the words like 英語, 先生, etc? , Sino-Japanese words can have a pronunciation of えい or ええ. According to jisho.org, the hiragana "げいしゃ" of "芸者" is based on on-yomi readings of the two kanji characters, which according to this comment in another question means that "芸者" is a Sino-Japanese word. This would suggest that "げえしゃ" is a valid pronunciation in Japanese.
However, I'm not 100% sure, partially because some people explicitly claim that "げえしゃ" or "geesha" isn't a valid pronunciation in Japanese. From a discussion page on Wikipedia:
I think to regard Geesha as a mispronunciation is not correct. In modern Japanese written "ei" is quite frequently pronounced as ee (i.e. long e) by Japanese native speakers. True, the Furagana based pronunciation as "ei" is also heard but the GIs stationed in Japan picked up the Geesha-pronunciation from native speakers.
No, it's not pronounced "geesha." Remember, basing pronunciation off of romanization is never a good idea.
And likewise, from the comments section of the blog post mentioned above, which seems in the first sentence to be talking at least somewhat about the pronunciation of words in Japanese:
Ditto Toranosuke here–Americans often don’t understand the “ei=ay not ee” rule. Similarly, my elementary schools think it’s hysterical when I teach them the American English pronunciation of words that came from Japanese (SUmo vs. suMOU, “kerry-okee” instead of “karaoke”), but I always tell them that an American will likely not understand what “suMOU” is…
Also, is there any difference in tone or nuance between the two pronunciations?
One blog post, Words that are different in Japanese and English, claims that in English, the word "geesha" has a different meaning to the word "geisha". The English-language Wikipedia article on geishas also claims that. I used to believe that, but now I regard it as unlikely. I suspect that it's more that people who pronounce it one way have a slightly different mental image of what a geisha is to people who pronounce it another way. However, is there any difference in Japanese between when it's pronounced "げえしゃ" or "げいしゃ"? The Japanese SE post on えい pronunciation claims that えい is more formal than ええ, which would be consistent with the difference between "geisha" and "geesha" in English according to the blog post.
To summarize: is "げえしゃ" a valid pronunciation of "芸者", and is there any difference in tone or nuance between it and "げいしゃ"?