I feel like a prick when I say it, but I do pronounce it foy-AY. That’s what my mom called it - she was raised in Cleveland by Polish parents.
My mom once found me passed out stone cold on the floor of her foy-AY after I’d been involved in a car accident. My injuries weren’t all that bad, but the casr-crash adreniline wore off as soon as I made it through the front door. Mmm… foy-AYs are a nice place to sleep it off.
I try to pronounce all French words with my authentic Saskatchewan accent.
One of my college pals was just like that: “Well, we were going to go to Paree, but decided at the last minute to head for Munchen, from which we could get to Ostberlin, then on to Moskva.”
Or something like that. We just rolled our eyes.
Foy-urr. I’ve never heard a live person pronounce it foy-yay, much less the more correctly French fwa-yay (+/-). I’m originally from SoCal & have lived in the southwest, FL, and now the midwest.
My attitude? What Attack from the 3rd dimension just said. It is now an English word pronounced according to English rules (such as they are).
I’m AmeRican. I pronounce it at foyeR. I can’t help it; it’s just part of my language repeRtoiRe.
This word doesn’t exist in my vocabulary. Whenever people say foyer, I hear “furrier” or “fourier” and have to kick my noodle into gear for a few seconds whilst I examine the context to see what the hell they meant.
Ahh, hallway. OK gotcha.
I’ll agree that switching to a French accent to pronounce Paris (unless you’re talking about gay Paree) is awkward; however, at least in architecture circles, foy-yay is a valid American pronunciation, even the dominant one in my experience. It’s actually not even that close to the French pronunciation - the consonants are the same, but the vowel sounds are fairly different.
ETA: Oh, and agreed that houses have hallways or entries, in my lexicon. Commercial buildings, however, often have foyers.
I usually just say it in French. I’m not a prick, I’m just French-Canadian. Deal with it. 
I would argue that anyone in a bilingual country gets to say any word from either language with either pronunciation. God knows where, when and from whom a Canadian learned any given word.
My current issue is that my kids say ‘conch’ as though it were ‘konch’, instead of ‘konk’. However, this only comes up when we are having a formal discussion and must pass the conch.
vestibule
I have to say that people who say For-Yer sound to me like people who say Buff-ett. 
For-Yer sounds like some hick pronunciation (hyuck, hyuck, and here’s our FOR-YER, 'cause it’s FOR YER coats and shoes)
Just sounds stilted and wrong to me. Always did, even before I learned French.
But then, hardly a deal breaker. 
That.
The whole thing sounds so impossibly pretentious, it has set me off wondering what kind of people would have a room that is not for anything but entering it and then entering some other real room from it.
I’ve heard it pronounced both ways, depending on where I was living at the time.
I think people who get their dick in a twist over regional variations in accents and pronunciations are flaming fucking assholes who seriously deserve to be banned from the internet. Forever.
Oh oh.
FOY-urr. It didn’t even occur to me that anyone would pronounce it any other way.
Then again, I also say “gar-AHJ” for garage, and I hear others pronounce it “garridge.”
I’ve always thought it was respectful to refer to proper nouns by their original names. Like when I was in Italy, I talked about Milano and Firenza and Venetzia. And I try to call ethnic groups what they call themselves.
Don’t have a particular logical argument, it just feels that way to me.
How do you pronouce Nicaragua without rolling your R’s? 
Currently poll results at 82 to 81. I have to say I’m surprised by how remarkably even the division is. I suspect the Canadians (and Brits?) are skewing it, if we had only Americans responding we’d see a majority for foy-urr.
Nick-ah-rah-gwa/Nick-er-ah-gwa. (Nick-er-ah-gew-ah if you’re on the BBC.) You’ve never heard an English speaker not roll their r’s when pronouncing Spanish names/loan words?
But then where would you find threads to join?