Let's see what you're trying to plot.
t=[0:0.1:50]
syms s
gs=1/(s^2 + 5*s + 6);
roots([1 5 6]);
gjw=fourier(gs)
If you want to evaluate gjw for w equal to each of the elements in t you can do this, and then you can plot the result.
syms w
gjw_at_t = subs(gjw, w, t);
plot(t, gjw_at_t)
You might want to plot the real and imaginary parts of gjw_at_t separately.
