Airlines don't care how many attempts experienced pilots took in their ATPLs, nor how many attempts hey took at the various flight tests, or even where they did their initial training. Once you have a couple of thousand hours (arguably considerably fewer) under your belt on a relevant type, none of the above is even considered.
However, when competing for entry level jobs (and especially airline jobs), employers can afford to be incredibly picky. A fail or two in the ATPLs, a second series IR/CPL etc. and your applications for that first job suddenly look considerably less competitive. That's not to say that you won't ever find a job, but an uphill struggle will become even tougher.