The general rule of thumb is 25, but Axure claims there is no actual limit. See the reference page for variables for more info: https://www.axure.com/support/reference/variables
Maybe… Not sure it would get you to your 200+ variables, but in terms of “native Axure” you could overload global variables with hashes or delimiters and represent multiple values in a single variable. Let’s say the first page of your survey has 5 questions: User Name (text field), Age (text field) and three multiple-choice questions (A-D answers). You could have a global variable, P1, that would get set with a value of “Joe Smith;36;D;B;A;” which could be later parsed with substring() or slice() functions. This should allow you to set dozens of responses to just one global variable. See https://forum.axure.com/t/v7-variables-list/24918 for a list of supported javascript functions (applies to RP8 and I believe RP9 too.) Learn more about each one by Googling its name, as in “javascript substring” or “javascript get last char in string” etc. (Note these are built-in Axure “variable functions” and not javascript injection.) You can also find these functions by looking in the “Insert Variable or Function…” link in the “fx” dialog under “String” or “Math”.
…Well, this perhaps more coding than you’d want, but I’m not a coder and learned it easily enough for these kind of purposes.
This may not work so well if you have open-ended or essay questions in your survey, as the total char count of your global variables may get too long. Performance will vary depending on the participant’s browser and computer as this is all “client-side” processing. You could potentially “hash” a long paragraph if you are really only interested in some keywords, for example if Q15 contains “depressed” or “depression” or “sad” or “unhappy” etc.
A few years ago I had maybe 5 to 10 questions on 20 pages (one survey page following a “UI page” or task in a prototype) and then used a javascript hack to print the page to a PDF. Most questions were repetitive, asking user to rate ease, time, confusion, etc. I learned it was easier to just administer and score the surveys manually or from video (screen recording) adding in ad-lib comments from user.
What about something like Survey Monkey? Does it have to be done in Axure or as a prototype?