Will it work? Maybe. It depends on a wide range of factors beyond the gain. Look into "Link Calculations" to see what you need to evaluate your situation.
How does one increase the gain? One place to look it to make the antenna more efficient by replacing elements with more efficient versions (lower loss tangents and increased conductivity). You might also address the impedance matching.
Added after 52 seconds:
Will it work? Maybe. It depends on a wide range of factors beyond the gain. Look into "Link Calculations" to see what you need to evaluate your situation.
How does one increase the gain? One place to look it to make the antenna more efficient by replacing elements with more efficient versions (lower loss tangents and increased conductivity). You might also address the impedance matching.