Both are correct. Some can replace plural countable nouns (verb in the plural) or mass nouns (verb in the singular).

There is some coffee in that cupboard. There's some in there. (uncountable noun)

A: Do you have any pencils?
B: Yes, there are some in that drawer. There are some in there. (countable noun, plural)

Both are correct. Some can replace plural countable nouns (verb in the plural) or mass nouns (verb in the singular).

There is some coffee in that cupboard. There's some in there. (uncountable noun)

A: Do you have any pencils?
B: Yes, there are some in that drawer. There are some in there. (countable noun, plural)

Edit: As for the use of there's (careful, not there is) followed by a plural noun, it is informal:

In speaking and in some informal writing, we use there’s even when it refers to more than one. This use could be considered incorrect in formal writing or in an examination:

• There’s three other people who are still to come.
• There’s lots of cars in the car park. (Cambridge)