My daughter turned 18 in June 2019 and started working for min wage in Aug 2019, can I still claim her for child tax credit and earned income credit? Does she still file?

[DoninGA]

You cannot claim the Child Tax Credit since she is older than 16.

You should be able to claim her as your dependent if she meets all the requirements under the Qualifying Child rules and EIC if you are eligible.

To be a Qualifying Child -

1. The child must be your son, daughter, stepchild, foster child, brother, sister, half brother, half sister, stepbrother, stepsister, or a descendant of any of them.
2. The child must be (a) under age 19 at the end of the year, (b) under age 24 at the end of the year and a full-time student or (c) any age and permanently and totally disabled.
3. The child must have lived with you for more than half of the year. Temporary absences while away at college are considered living with you.
4. The child must not have provided more than half of his or her own support for the year.
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child.
6. The child must be a U.S. citizen or U.S., Canada or Mexico resident for some portion of the year.
7. The child must be younger than you unless disabled.

[DoninGA]

She can file a tax return and indicate on her return that she can be claimed as a dependent.

[Hal_Al]

There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, a relationship test and residence test. Only a QC qualifies a taxpayer for the Earned Income Credit and the Child Tax Credit (must be under 17). 

Since she is under 19, she can be your QC, as long as she lived with you more than half the year.  

It doesn't matter how much she earned. What matters is how much she spent on support. Money she put into savings does not count as support he spent on her self.

The support value of the home, provided by the parent, is the fair market rental value of the home plus utilities & other expenses divided by the number of occupants.