[name_m]Just[/name_m] from an English-speaking context, I’d probably half expect [name_m]Fabian[/name_m] to be FAY-bee-uhn, while [name_m]Fabien[/name_m] would be FAB-ye / FA-bee-uhn (Fay rhyming with day and Fab rhyming with cab or lab). However, I wouldn’t be surprised by different pronunciations.
[name_f][/name_f]I think [name_m]Fabien[/name_m] would be fine to use 