I believe that he might or have sage mode, it would have certainly made sense for Jiraiya to teach him, giving that it would dramatically increase his close to close skills.
Allot of people are talking about why didn't he use it against Tobi, well tbh! There would have been a number of reasons.
He may not have wanted to waste time, getting into sage mode while his village was getting destroyed and giving the fact that figured out rather quickly that he wasn't able to hit him, due to his In-tangible effect, it would make sense.
You see sage mode increases your physical strength and speed, although... Strength wouldn't matter giving that he can't touch him, and speed well... Nothing less of Instant is fast enough to hit Obito, and He doesn't actually need sage mode to use FTG effectively.
There is another big reason that it probably the biggest reason that we have not seen, giving that he has the ability of course. The reason is that Kish doesn't want to show it.... It wouldn't surprise me if he wanted to save some of his techniques for his return. It would make of a awesome hidden techniques....
This is all merely speculation of course, noone can really tell you for sure wither or not he has the ability although, giving that Naruto received the Training, it wouldn't be off to in stating that Minato undertook the same training.
Everyone has different opinion, if you don't agree then that's fine! I respect your opinion, all the same.