Think about it this way. 3^y increases more rapidly than 2^y. Originally 8*2^y has a large start. But each time when y increases, the value of function 3^y increases three times the previous value, while the other function only increases twice the previous value. Some point on the way the more rapidly increasing function is due to surpass the slower increasing function.
Keep on asking, and it will be given you;
keep on seeking, and you will find;
keep on knocking, and it will be opened to you.