Does he have to do ghusl if he only sees a non-mahram woman or talks to her?

No File Exists
Check below answers in case you are looking for other related questions:
Dealing with the fitnah (temptation) of women
First and second glance at women

No File Exists
Related Answers:
Resisting sexual desires
He did ghusl with the intention of doing it for Jumu‘ah and he forgot about doing it for janaabah; did it remove his impurity?
Ruling on rubbing thick hair when doing ghusl for janaabah
Dealing with the fitnah (temptation) of women
First and second glance at women

Recommended answers for you:
Neglecting prayer out of laziness
Is there a set age for marriage in Islam?
Ruling on making du’aa’ in languages other than Arabic in the prayer
Etiquette of making du’aa’
Sleep invalidates wudoo’ if it is deep