Yes, I practice zazen meditation and it is my belief that it can have a tremendous effect on technique and mindset.
Zazan creates stillness of mind, which most traditional martial artists value greatly. It gives one an ability to contemplate his techniques in a clearer way during training and a mind like water. One with a mind like water can then proceed to react in the best way to any situation that may arise.
I also believe that zazen can produce harmony within the energies of the body, which promotes strength, reflexes, awareness, thought, and much more. An extremely old belief is that if you maintain this balance, you can avoid sickness as well.
So, according to many martial arts teachings; yes, it will help a great deal.
Personally, I encourage you to read a book on this subject and see for yourself how much it benefits you.