Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Gabriel was more common in the past and has since settled at a lower, steady level. All-time it's been given to 402,627 U.S. babies, the 79th most common name by sound today, peaking at 13,188 in 2008, with 6,579 in 2025.
Gabriel has no common alternate spellings by sound.