The choice between the two would come down to which thing you wanted to emphasize, either her or it.

If you wanted to emphasize that who needs to be talked to is more important than the thing, then the first sentence stresses this.

If you wanted to emphasize that the thing is more important than who it is being talked to, then the second sentence would stress this.

"Talk to (a person)" is given by dictionaries such as the Collins online dictionary and the Oxford Learner's Dicitonaries, but "talk with" is common in spoken American/Canadian English.

"Talk to" is sometimes avoided because of the connotation of "talking down" to a person (such as a manager talking to an employee or a teacher talking to a student), and "talk with" is sometimes used by important people to minimize the social distance between them and their audience.

Example: The U.S. President Obama in 2014.

"My fellow Americans, tonight, I’d like to talk with you about immigration."

source: https://obamawhitehouse.archives.gov/the-press-office/2014/11/20/remarks-President-address-nation-immigration

Also, "talk with" can describe the manner of talking.

He talked with anger in his voice.

He talked with a cigarette in his mouth.

First it is better to say "talk to her" not "talk with her" with is more often used with other verbs like speak or chat and ....

Both setnences are correct. It depends on what you are going to concentrate. If you are gonna concentrate on her then say:

You gotta talk to her about it.

There is perfect grammar (usually written) and then there is what we actually say. Both of these are correct for spoken English and, If you use them, you will be understood.