Gayle, playing his first Test for more than 18 months due to his stand-off with the West Indies Cricket Board, finished the second day on 85 not out while his opening partner Kieran Powell was unbeaten on 58 as the Windies closed on 145 without loss.
That was 206 runs behind New Zealand after they were bowled out for 351, with West Indies spinner Sunil Narine finishing with five for 132 - his maiden five-wicket haul in only his second Test - after adding two more wickets to his three scalps from day one.
The Black Caps were only able to add 119 runs to their overnight tally of 232 for four before being dismissed in the afternoon session.
It would have been even worse for the tourists but for a counter-attacking 39 off 31 by number 10 Doug Bracewell, who put on 42 for the final wicket with Chris Martin (four not out).
Gayle and Powell then followed up the good work done by the bowlers with the West Indies' best opening stand since 2006.
Gayle hit four successive boundaries off the first over from Martin and added six more in reaching his 34th Test fifty. The big-hitting left-hander did get a life when on 37 though when he was dropped by Daniel Flynn at point.
The 32-year-old slowed down towards the end of the day but still added two more fours and a six to his tally, having faced just 124 balls in total.
Powell, meanwhile, was more circumspect in making his third Test fifty with the 22-year-old's runs coming off 164 balls and included 10 fours.