The answer is affirmative. There exist 2018 distinct positive numbers satisfying the required conditions:
a,2a,…,2018a, where a=(62018⋅2019⋅4037)4.
Note that a is an integer number, since 2019 is a multiple of 3 and 2018 is a multiple of 2.
The sum of the squares of these numbers is
a2+(2a)2+⋯+(2018a)2=a2(12+22+⋯+20182)=a2(62018⋅2019⋅4037)==(62018⋅2019⋅4037)8(62018⋅2019⋅4037)=((62018⋅2019⋅4037)3)3,
which is a perfect cube, and the sum of their cubes is
a3+(2a)3+⋯+(2018a)3=a3(13+23+⋯+20183)=a3(22018⋅2019)2==(62018⋅2019⋅4037)12(22018⋅2019)2=((62018⋅2019⋅4037)6(22018⋅2019))2,
which is a perfect square.