Import termset from CSV file. CSV format is standard TermSet format.

ImportTermsetFromCSV.ps1

# ----------------------------------------------
# Author: Microsoft
# Date: 27.02.2014
# Description: Import termset from CSV file. 
# ----------------------------------------------

function ImportTermSet([Microsoft.SharePoint.Taxonomy.TermStore]$store, [string]$groupName, [PSCustomObject]$termSet) {  
  function ImportTerm([Microsoft.SharePoint.Taxonomy.Group]$group, 
                      [Microsoft.SharePoint.Taxonomy.TermSet]$set, 
                      [Microsoft.SharePoint.Taxonomy.Term]$parent, 
                      [string[]]$path) {       	
    if ($path.Length -eq 0) {
      return
    } elseif ($group -eq $null) {
      $group = $store.Groups | where { $_.Name -eq $path[0] }
      if ($group -eq $null) {
        $group = $store.CreateGroup($path[0])
      }
    } elseif ($set -eq $null) {
      $set = $group.TermSets | where { $_.Name -eq $path[0] }
      if ($set -eq $null) {
        $set = $group.CreateTermSet($path[0])
      }
    } else {
      $node = if ($parent -eq $null) { $set } else { $parent }
      $parent = $node.Terms | where { $_.Name -eq $path[0] }  	   
      if ($parent -eq $null) {
        $parent = $node.CreateTerm($path[0], 1033)
      } 
    }
    
    ImportTerm $group $set $parent $path[1..($path.Length)]					
  }
  
  function RemoveTermGroup([Microsoft.SharePoint.Taxonomy.TermStore]$store, [string]$groupName) {
    $group = $store.Groups | where { $_.Name -eq $groupName }
    if ($group -ne $null) {
      $group.TermSets | foreach { $_.Delete() }
      $group.Delete()
      $store.CommitAll()
    }
  }
  
  RemoveTermGroup $store $groupName
  $termSetName = $termSet[0]."Term Set Name"    
  $termSet | where { $_."Level 1 Term" -ne "" } | foreach {
    $path = @($groupName, $termSetName) + @(for ($i = 1; $i -le 7; $i++) { 
      $term = $_."Level $i Term"
        if ($term -eq "") {
          break
        } else {
          $term
        }
      }
    )
	
    ImportTerm -path $path
  }
}

$session = Get-SPTaxonomySession -Site "http://localhost"
$store = $session.TermStores["Managed Metadata Service"]   
$termSet = Import-Csv "C:\Users\Ronnie\Desktop\ImportTermSet.csv"
ImportTermSet $store "MyGroup" $termSet
$store.CommitAll()

Termset-Sample.csv