ANSWER
Samuel will have 28 ounces of juice
Yes, it will be able to fill a one-quart container
Step-by-step explanation
The first container was 1/2 full of juice.
The second container was 1/4 full of juice.
The third container was 1/8 full of juice.
Note: Each container is a one quart container.
To find how many ounces of Juice Sam will have, we have to first calculate the total amount of quarts of juice that he has.
That is:

We have that:
1 quart = 32 ounces
=> 7/8 quart = 32 * 7/8 = 28 ounces
Samuel will have 28 ounces of juice.
As earlier calculated, Samuel has 7/8 quart of juice.
So, yes, it will be able to fill a one-quart container.