Should heel up fine by the time of the fight, plus its located on the cheekbone where even if it were to open up its not in a dangerous place where its going to interfere with his sight.
I wouldn't be surprised If it's delayed by a few weeks, it all depends, broken skin around the eyes isn't a good thing. It will heal in time for the fight but it's more to do with his sparring and how that will impact on his training schedule.
I think this cut recovers completely in ~15 days. Plant'll have full one month for sparring. Plant's face got f*cked worse than this in the Uzcátegui fight, he is experienced.