Beamer - Multiple Authors - Formatting the title page

You can use only two columns instead of four; the leftmost column will contain the authors, and the rightmost one, the logo:

\documentclass{beamer}
\usetheme{CambridgeUS}
\useoutertheme{infolines}

\usepackage{tikz}

\newcommand\RBox[1]{%
  \tikz\node[draw,rounded corners,align=center,] {#1};%
}  

\setbeamerfont{author in head/foot}{size={\fontsize{3pt}{4pt}\selectfont}}
\author[Subham \& Mithun \& Karthikeyan \& Shantikumar]
{%
   \texorpdfstring{
        \begin{columns}
            \column{.45\linewidth}
            \centering
            \includegraphics[width=\linewidth]{ctanlion}
            \column{.45\linewidth}
            \centering
            \RBox{Subham Soni S.\\
            \href{mailto:[email protected]}{[email protected]}}\\[0.5ex]
            \RBox{Karthikeyan\\
            \href{mailto:[email protected]}{[email protected]}}\\[0.5ex]
            \RBox{Mithun C.K.\\
            \href{mailto:[email protected]}{[email protected]}}\\[0.5ex]
            \RBox{Shantikumar L.\\
            \href{mailto:[email protected]}{[email protected]}}
        \end{columns}
   }
   {Subham Soni S., Karthikeyanm, Shantikumar L.,  Mithun C.K.}
}
\title{Work Culture}

\begin{document}

\begin{frame}
\titlepage
\end{frame}

\end{document}

Notice also the line

\setbeamerfont{author in head/foot}{size={\fontsize{3pt}{4pt}\selectfont}}

to reduce the font for the authors in the footline so they fit in the available space.

_{CTAN lion drawing by Duane Bibby.}

This is another possible layout:

\documentclass{beamer}
\usetheme{CambridgeUS}
\useoutertheme{infolines}
\usepackage{tikz}
\newcommand\RBox[1]{%
  \tikz\node[draw,rounded corners,align=center,] {#1};%
}  
\author[Subham Soni S. \& Mithun C.K. \& Karthikeyan \& Shantikumar L.]
{%
   \texorpdfstring{
        \begin{columns}
            \column{.45\linewidth}
            \centering
            \RBox{Subham Soni S.\\
            \href{mailto:[email protected]}{[email protected]}}
            \column{.45\linewidth}
            \centering
            \RBox{Mithun C.K.\\
            \href{mailto:[email protected]}{[email protected]}}
        \end{columns}
        \vspace{0.5cm}
        \begin{columns}
            \column{.45\linewidth}
            \centering
            \RBox{Karthikeyan\\
            \href{mailto:[email protected]}{[email protected]}}
            \column{.45\linewidth}
            \centering
            \RBox{Shantikumar L.\\
            \href{mailto:[email protected]}{[email protected]}}
        \end{columns}
        \vspace{-0.3cm}
        \begin{columns}
          \column{0.3\linewidth}
          \raggedleft
            \includegraphics[width=0.7cm]{pecemblem}
            \vspace{-4.8cm}
            \column{0.6\linewidth}
            \raggedright
            Department of CSE\\[1.1ex]
            PEC\\
            \vspace{-4.8cm}
        \end{columns}
   }
   {John Doe \& Jane Doe}
}
\title{Work Culture}
\begin{document}
\begin{frame}
\titlepage
\end{frame}
\end{document}

Adding these lines to the definition of \RBox

\usetikzlibrary{shadows}
\newcommand\RBox[1]{%
  \tikz\node[draw,rounded corners,align=center,double copy shadow={opacity=0.3,shadow xshift=1ex,shadow yshift=-0.5ex,left color = brown!40,right color = magenta!80},left color=blue!50,right color=green!50 ] {#1};%

gives

_{I am bad too in color choice :(}