I was able to increase width of the column but I want to increase the space between \cventry that is date and the contents.
This length is controlled by \separatorcolumnwidth which is set to
in moderncvstyleclassic.sty. Update this in the preamble to suit your needs. Below is the default (left) output compared to setting it to .2\textwidth (using template.tex):
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6 months ago
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