Has their use of Gaelic affected their use of English? I ask because I used to have a job that occasionally required me to take customer calls from Canada. On a number of occasions I got calls from French speakers from Quebec and they couldn’t speak English to me. They also appeared not to understand me at all.
No, it doesn’t although because of the Gaelic, the Irish have trouble with the “th” sound which doesn’t exist in their own language. It’s why they’ll say “tink” instead of “think.” (Of course, I’m sure many Irish take pains to pronounce English words correctly.) But they’re all fluent in English.