A gimmick would help keep the wrestler popular with fans, so more bookings and more money. But I don't think the gimmick alone was enough. Lord Bertie Topham and The original Undertaker being cases in point. Great gimmicks, but not big time. Maxine's Goldbelt gimmick probably extended his lifespan, though promoters could have got rid of him if they wanted to. So the gimmick did help, but only after the wrestler had established himself as a reliable, trustworthy and capable worker. The wrestler maketh the gimmick, not the gimmick maketh the wrestler.
A gimmick would help keep the wrestler popular with fans, so more bookings and more money. But I don't think the gimmick alone was enough. Lord Bertie Topham and The original Undertaker being cases in point. Great gimmicks, but not big time. Maxine's Goldbelt gimmick probably extended his lifespan, though promoters could have got rid of him if they wanted to. So the gimmick did help, but only after the wrestler had established himself as a reliable, trustworthy and capable worker. The wrestler maketh the gimmick, not the gimmick maketh the wrestler.